diff --git a/include/tinycsocket.h b/include/tinycsocket.h
index ece087d..92f7e64 100644
--- a/include/tinycsocket.h
+++ b/include/tinycsocket.h
@@ -29,7 +29,7 @@
 #ifndef TINYCSOCKET_INTERNAL_H_
 #define TINYCSOCKET_INTERNAL_H_
 
-static const char* const TCS_VERSION_TXT = "v0.3.86";
+static const char* const TCS_VERSION_TXT = "v0.3.87";
 extern const char* const TCS_LICENSE_TXT;
 
 /*
@@ -569,7 +569,7 @@ TcsResult tcs_socket(TcsSocket* out_socket, TcsFamily family, TcsSocketType type
 *
 * Creates an IPv4 or IPv6 TCP socket based on the address family of the provided address(es).
 * If @p local_address is not NULL, SO_REUSEADDR is set and the socket is bound to it.
-* If @p remote_address is not NULL, the socket connects to it.
+* If @p remote_address is not NULL, the socket connects to it, so it must have a port.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * If both are provided, they must have the same address family.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
@@ -606,7 +606,7 @@ TcsResult tcs_socket(TcsSocket* out_socket, TcsFamily family, TcsSocketType type
 * @param[in] timeout_ms maximum time in milliseconds to wait for connection, or #TCS_WAIT_INF for OS default timeout. Ignored if @p remote_address is NULL.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, or if both are provided with different address families.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if both are provided with different address families, or if @p remote_address has port 0.
 * @retval #TCS_ERROR_CONNECTION_REFUSED if the remote server refused the connection.
 * @retval #TCS_ERROR_TIMED_OUT if the connection attempt timed out.
 *
@@ -623,7 +623,9 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
 * @brief Create a TCP socket from string addresses, optionally bind and/or connect.
 *
 * Resolves the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_tcp().
-* Addresses must include a port, e.g. "127.0.0.1:8080" or "[::1]:8080".
+* Addresses are given as "host:port", e.g. "localhost:8080", "127.0.0.1:8080" or "[::1]:8080".
+* The first resolved address is used. @p remote_address must include a port.
+* @p local_address without a port binds to a port chosen by the operating system.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
 *
@@ -654,7 +656,8 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
 * @param[in] timeout_ms maximum time in milliseconds to wait for connection, or #TCS_WAIT_INF for OS default timeout. Ignored if @p remote_address is NULL.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, or if both addresses are NULL.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if an address string is malformed, or if @p remote_address has no port.
+* @retval #TCS_ERROR_ADDRESS_LOOKUP_FAILED if an address string could not be resolved.
 * @retval #TCS_ERROR_CONNECTION_REFUSED if the remote server refused the connection.
 * @retval #TCS_ERROR_TIMED_OUT if the connection attempt timed out.
 *
@@ -677,6 +680,7 @@ TcsResult tcs_socket_tcp_str(TcsSocket* out_socket,
 * When only @p remote_address is given (no @p local_address), the socket is also connected,
 * allowing use of ::tcs_send(). When both are given, the socket is not connected to avoid
 * filtering out multicast traffic — use ::tcs_send_to() instead.
+* Whenever the socket is connected, @p remote_address must have a port.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * If both are provided, they must have the same address family.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
@@ -712,7 +716,7 @@ TcsResult tcs_socket_tcp_str(TcsSocket* out_socket,
 * @param[in] remote_address address to connect to, or NULL to skip connecting.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, or if both are provided with different address families.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if both are provided with different address families, or if @p remote_address is connected to but has port 0.
 *
 * @see tcs_socket_udp_str()
 * @see tcs_close()
@@ -724,8 +728,10 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 /**
 * @brief Create a UDP socket from string addresses, optionally bind and/or connect.
 *
-* Parses the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_udp().
-* Addresses must include a port, e.g. "127.0.0.1:8080" or "[::1]:8080".
+* Resolves the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_udp().
+* Addresses are given as "host:port", e.g. "localhost:8080", "127.0.0.1:8080" or "[::1]:8080".
+* The first resolved address is used. A @p remote_address that the socket connects to must include a port.
+* @p local_address without a port binds to a port chosen by the operating system.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
 *
@@ -755,7 +761,8 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 * @param[in] remote_address address string to connect to, or NULL to skip connecting.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, or if both addresses are NULL.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if an address string is malformed, or if @p remote_address is connected to but has no port.
+* @retval #TCS_ERROR_ADDRESS_LOOKUP_FAILED if an address string could not be resolved.
 *
 * @see tcs_socket_udp()
 * @see tcs_close()
@@ -1831,7 +1838,17 @@ TcsResult tcs_interface_list(struct TcsInterface out_interfaces[], size_t interf
 /**
 * @brief Resolve a hostname to one or more addresses.
 *
-* @param[in] hostname hostname or IP string to resolve.
+* The string may include a port, which is then set on every returned address:
+* @verbatim
+* localhost
+* localhost:1212
+* 192.168.0.1:1212
+* [::1]:1212
+* @endverbatim
+* Numeric addresses are parsed with ::tcs_address_parse() without any lookup.
+* Without a port, the port of the returned addresses is 0.
+*
+* @param[in] hostname hostname or IP string to resolve, optionally with a port.
 * @param[in] address_family address family filter, or ::TCS_FAMILY_ANY for all.
 * @param[out] out_addresses array to receive resolved addresses, or NULL to only count.
 * @param[in] addresses_length number of elements in the @p out_addresses array.
@@ -4022,6 +4039,35 @@ TcsResult tcs_address_resolve(const char* hostname,
     if (address_family.native == -1) // sentinel for unsupported families (e.g. TCS_FAMILY_PACKET on non-Linux)
         return TCS_ERROR_NOT_SUPPORTED;
 
+    // getaddrinfo() does not understand "hostname:port". A string with exactly one ':' carries a port, which is
+    // split off here and applied to the results. Brackets belong to numeric IPv6 only, handled by the fast path.
+    if (strpbrk(hostname, "[]") != NULL)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    char host[256]; // Hostnames are at most 253 characters
+    uint16_t port = 0;
+    const char* colon = strchr(hostname, ':');
+    bool has_port = colon != NULL && strchr(colon + 1, ':') == NULL;
+    size_t host_size = has_port ? (size_t)(colon - hostname) : strlen(hostname);
+    if (host_size == 0 || host_size >= sizeof host)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (has_port)
+    {
+        if (colon[1] == '\0')
+            return TCS_ERROR_INVALID_ARGUMENT;
+        unsigned long port_value = 0;
+        for (const char* c = colon + 1; *c != '\0'; ++c)
+        {
+            if (*c < '0' || *c > '9')
+                return TCS_ERROR_INVALID_ARGUMENT;
+            port_value = port_value * 10 + (unsigned long)(*c - '0');
+            if (port_value > 65535)
+                return TCS_ERROR_INVALID_ARGUMENT;
+        }
+        port = (uint16_t)port_value;
+    }
+    memcpy(host, hostname, host_size);
+    host[host_size] = '\0';
+
     struct addrinfo native_hints;
     memset(&native_hints, 0, sizeof native_hints);
     native_hints.ai_family = address_family.native;
@@ -4030,7 +4076,7 @@ TcsResult tcs_address_resolve(const char* hostname,
     native_hints.ai_protocol = IPPROTO_UDP;
 
     struct addrinfo* native_addrinfo_list = NULL;
-    int sts = getaddrinfo(hostname, NULL, &native_hints, &native_addrinfo_list);
+    int sts = getaddrinfo(host, NULL, &native_hints, &native_addrinfo_list);
 
     // TODO: Move error codes to errno2retcode()
     if (sts == EAI_SYSTEM)
@@ -4069,6 +4115,10 @@ TcsResult tcs_address_resolve(const char* hostname,
             TcsResult convert_address_status = native2sockaddr(iter->ai_addr, &out_addresses[i]);
             if (convert_address_status != TCS_SUCCESS)
                 continue;
+            if (out_addresses[i].family.native == TCS_FAMILY_IPV4.native)
+                out_addresses[i].data.ipv4.port = port;
+            else if (out_addresses[i].family.native == TCS_FAMILY_IPV6.native)
+                out_addresses[i].data.ipv6.port = port;
             i++;
         }
     }
@@ -6923,12 +6973,41 @@ TcsResult tcs_address_resolve(const char* hostname,
     if (address_family.native == TCS_FAMILY_PACKET.native) // Only the numeric fast path above can give a MAC address
         return TCS_ERROR_NOT_SUPPORTED;
 
+    // getaddrinfo() does not understand "hostname:port". A string with exactly one ':' carries a port, which is
+    // split off here and applied to the results. Brackets belong to numeric IPv6 only, handled by the fast path.
+    if (strpbrk(hostname, "[]") != NULL)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    char host[256]; // Hostnames are at most 253 characters
+    uint16_t port = 0;
+    const char* colon = strchr(hostname, ':');
+    bool has_port = colon != NULL && strchr(colon + 1, ':') == NULL;
+    size_t host_size = has_port ? (size_t)(colon - hostname) : strlen(hostname);
+    if (host_size == 0 || host_size >= sizeof host)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (has_port)
+    {
+        if (colon[1] == '\0')
+            return TCS_ERROR_INVALID_ARGUMENT;
+        unsigned long port_value = 0;
+        for (const char* c = colon + 1; *c != '\0'; ++c)
+        {
+            if (*c < '0' || *c > '9')
+                return TCS_ERROR_INVALID_ARGUMENT;
+            port_value = port_value * 10 + (unsigned long)(*c - '0');
+            if (port_value > 65535)
+                return TCS_ERROR_INVALID_ARGUMENT;
+        }
+        port = (uint16_t)port_value;
+    }
+    memcpy(host, hostname, host_size);
+    host[host_size] = '\0';
+
     ADDRINFOA native_hints;
     memset(&native_hints, 0, sizeof native_hints);
     native_hints.ai_family = address_family.native;
 
     PADDRINFOA native_addrinfo_list = NULL;
-    int getaddrinfo_status = getaddrinfo(hostname, NULL, &native_hints, &native_addrinfo_list);
+    int getaddrinfo_status = getaddrinfo(host, NULL, &native_hints, &native_addrinfo_list);
     if (getaddrinfo_status != 0)
         return TCS_ERROR_ADDRESS_LOOKUP_FAILED;
 
@@ -6950,6 +7029,10 @@ TcsResult tcs_address_resolve(const char* hostname,
             TcsResult address_convert_status = native2sockaddr(iter->ai_addr, &out_addresses[i]);
             if (address_convert_status != TCS_SUCCESS)
                 continue;
+            if (out_addresses[i].family.native == TCS_FAMILY_IPV4.native)
+                out_addresses[i].data.ipv4.port = port;
+            else if (out_addresses[i].family.native == TCS_FAMILY_IPV6.native)
+                out_addresses[i].data.ipv6.port = port;
             i++;
         }
     }
@@ -7292,6 +7375,13 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
     if (local_address != NULL && remote_address != NULL &&
         local_address->family.native != remote_address->family.native)
         return TCS_ERROR_INVALID_ARGUMENT;
+    // A remote address without a port can never be connected to
+    if (remote_address != NULL && remote_address->family.native == TCS_FAMILY_IPV4.native &&
+        remote_address->data.ipv4.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (remote_address != NULL && remote_address->family.native == TCS_FAMILY_IPV6.native &&
+        remote_address->data.ipv6.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
     if (timeout_ms < 0 && timeout_ms != TCS_WAIT_INF)
         return TCS_ERROR_INVALID_ARGUMENT;
 
@@ -7443,6 +7533,15 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
         local_address->family.native != remote_address->family.native)
         return TCS_ERROR_INVALID_ARGUMENT;
 
+    // A multicast group joined on a bound socket is the only remote address the socket is not connected to
+    bool is_multicast = remote_address != NULL && tcs_address_is_multicast(remote_address);
+    bool do_connect = remote_address != NULL && (!is_multicast || local_address == NULL);
+    // A remote address without a port can never be connected to
+    if (do_connect && remote_address->family.native == TCS_FAMILY_IPV4.native && remote_address->data.ipv4.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (do_connect && remote_address->family.native == TCS_FAMILY_IPV6.native && remote_address->data.ipv6.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+
     TcsFamily family = local_address != NULL ? local_address->family : remote_address->family;
 
     TcsResult res = tcs_socket(out_socket, family, TCS_SOCKET_DGRAM, TCS_PROTOCOL_IP_UDP);
@@ -7467,8 +7566,6 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 
     if (remote_address != NULL)
     {
-        bool is_multicast = tcs_address_is_multicast(remote_address);
-
         if (is_multicast)
         {
             res = tcs_opt_membership_add(*out_socket, remote_address);
@@ -7479,7 +7576,7 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
             }
         }
 
-        if (!is_multicast || local_address == NULL)
+        if (do_connect)
         {
             res = tcs_connect(*out_socket, remote_address);
             if (res != TCS_SUCCESS)
diff --git a/src/tinycsocket_common.c b/src/tinycsocket_common.c
index 087755c..422eed3 100644
--- a/src/tinycsocket_common.c
+++ b/src/tinycsocket_common.c
@@ -130,6 +130,13 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
     if (local_address != NULL && remote_address != NULL &&
         local_address->family.native != remote_address->family.native)
         return TCS_ERROR_INVALID_ARGUMENT;
+    // A remote address without a port can never be connected to
+    if (remote_address != NULL && remote_address->family.native == TCS_FAMILY_IPV4.native &&
+        remote_address->data.ipv4.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (remote_address != NULL && remote_address->family.native == TCS_FAMILY_IPV6.native &&
+        remote_address->data.ipv6.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
     if (timeout_ms < 0 && timeout_ms != TCS_WAIT_INF)
         return TCS_ERROR_INVALID_ARGUMENT;
 
@@ -281,6 +288,15 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
         local_address->family.native != remote_address->family.native)
         return TCS_ERROR_INVALID_ARGUMENT;
 
+    // A multicast group joined on a bound socket is the only remote address the socket is not connected to
+    bool is_multicast = remote_address != NULL && tcs_address_is_multicast(remote_address);
+    bool do_connect = remote_address != NULL && (!is_multicast || local_address == NULL);
+    // A remote address without a port can never be connected to
+    if (do_connect && remote_address->family.native == TCS_FAMILY_IPV4.native && remote_address->data.ipv4.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (do_connect && remote_address->family.native == TCS_FAMILY_IPV6.native && remote_address->data.ipv6.port == 0)
+        return TCS_ERROR_INVALID_ARGUMENT;
+
     TcsFamily family = local_address != NULL ? local_address->family : remote_address->family;
 
     TcsResult res = tcs_socket(out_socket, family, TCS_SOCKET_DGRAM, TCS_PROTOCOL_IP_UDP);
@@ -305,8 +321,6 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 
     if (remote_address != NULL)
     {
-        bool is_multicast = tcs_address_is_multicast(remote_address);
-
         if (is_multicast)
         {
             res = tcs_opt_membership_add(*out_socket, remote_address);
@@ -317,7 +331,7 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
             }
         }
 
-        if (!is_multicast || local_address == NULL)
+        if (do_connect)
         {
             res = tcs_connect(*out_socket, remote_address);
             if (res != TCS_SUCCESS)
diff --git a/src/tinycsocket_internal.h b/src/tinycsocket_internal.h
index a045373..8a02469 100644
--- a/src/tinycsocket_internal.h
+++ b/src/tinycsocket_internal.h
@@ -23,7 +23,7 @@
 #ifndef TINYCSOCKET_INTERNAL_H_
 #define TINYCSOCKET_INTERNAL_H_
 
-static const char* const TCS_VERSION_TXT = "v0.3.86";
+static const char* const TCS_VERSION_TXT = "v0.3.87";
 extern const char* const TCS_LICENSE_TXT;
 
 /*
@@ -563,7 +563,7 @@ TcsResult tcs_socket(TcsSocket* out_socket, TcsFamily family, TcsSocketType type
 *
 * Creates an IPv4 or IPv6 TCP socket based on the address family of the provided address(es).
 * If @p local_address is not NULL, SO_REUSEADDR is set and the socket is bound to it.
-* If @p remote_address is not NULL, the socket connects to it.
+* If @p remote_address is not NULL, the socket connects to it, so it must have a port.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * If both are provided, they must have the same address family.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
@@ -600,7 +600,7 @@ TcsResult tcs_socket(TcsSocket* out_socket, TcsFamily family, TcsSocketType type
 * @param[in] timeout_ms maximum time in milliseconds to wait for connection, or #TCS_WAIT_INF for OS default timeout. Ignored if @p remote_address is NULL.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, or if both are provided with different address families.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if both are provided with different address families, or if @p remote_address has port 0.
 * @retval #TCS_ERROR_CONNECTION_REFUSED if the remote server refused the connection.
 * @retval #TCS_ERROR_TIMED_OUT if the connection attempt timed out.
 *
@@ -617,7 +617,9 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
 * @brief Create a TCP socket from string addresses, optionally bind and/or connect.
 *
 * Resolves the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_tcp().
-* Addresses must include a port, e.g. "127.0.0.1:8080" or "[::1]:8080".
+* Addresses are given as "host:port", e.g. "localhost:8080", "127.0.0.1:8080" or "[::1]:8080".
+* The first resolved address is used. @p remote_address must include a port.
+* @p local_address without a port binds to a port chosen by the operating system.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
 *
@@ -648,7 +650,8 @@ TcsResult tcs_socket_tcp(TcsSocket* out_socket,
 * @param[in] timeout_ms maximum time in milliseconds to wait for connection, or #TCS_WAIT_INF for OS default timeout. Ignored if @p remote_address is NULL.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, or if both addresses are NULL.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if an address string is malformed, or if @p remote_address has no port.
+* @retval #TCS_ERROR_ADDRESS_LOOKUP_FAILED if an address string could not be resolved.
 * @retval #TCS_ERROR_CONNECTION_REFUSED if the remote server refused the connection.
 * @retval #TCS_ERROR_TIMED_OUT if the connection attempt timed out.
 *
@@ -671,6 +674,7 @@ TcsResult tcs_socket_tcp_str(TcsSocket* out_socket,
 * When only @p remote_address is given (no @p local_address), the socket is also connected,
 * allowing use of ::tcs_send(). When both are given, the socket is not connected to avoid
 * filtering out multicast traffic — use ::tcs_send_to() instead.
+* Whenever the socket is connected, @p remote_address must have a port.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * If both are provided, they must have the same address family.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
@@ -706,7 +710,7 @@ TcsResult tcs_socket_tcp_str(TcsSocket* out_socket,
 * @param[in] remote_address address to connect to, or NULL to skip connecting.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, or if both are provided with different address families.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if both are provided with different address families, or if @p remote_address is connected to but has port 0.
 *
 * @see tcs_socket_udp_str()
 * @see tcs_close()
@@ -718,8 +722,10 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 /**
 * @brief Create a UDP socket from string addresses, optionally bind and/or connect.
 *
-* Parses the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_udp().
-* Addresses must include a port, e.g. "127.0.0.1:8080" or "[::1]:8080".
+* Resolves the address strings with ::tcs_address_resolve() and delegates to ::tcs_socket_udp().
+* Addresses are given as "host:port", e.g. "localhost:8080", "127.0.0.1:8080" or "[::1]:8080".
+* The first resolved address is used. A @p remote_address that the socket connects to must include a port.
+* @p local_address without a port binds to a port chosen by the operating system.
 * At least one of @p local_address or @p remote_address must be non-NULL.
 * On failure, *out_socket is always set back to #TCS_SOCKET_INVALID.
 *
@@ -749,7 +755,8 @@ TcsResult tcs_socket_udp(TcsSocket* out_socket,
 * @param[in] remote_address address string to connect to, or NULL to skip connecting.
 *
 * @return #TCS_SUCCESS if successful, otherwise the error code.
-* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, or if both addresses are NULL.
+* @retval #TCS_ERROR_INVALID_ARGUMENT if @p out_socket is NULL, if *out_socket is not #TCS_SOCKET_INVALID, if both addresses are NULL, if an address string is malformed, or if @p remote_address is connected to but has no port.
+* @retval #TCS_ERROR_ADDRESS_LOOKUP_FAILED if an address string could not be resolved.
 *
 * @see tcs_socket_udp()
 * @see tcs_close()
@@ -1825,7 +1832,17 @@ TcsResult tcs_interface_list(struct TcsInterface out_interfaces[], size_t interf
 /**
 * @brief Resolve a hostname to one or more addresses.
 *
-* @param[in] hostname hostname or IP string to resolve.
+* The string may include a port, which is then set on every returned address:
+* @verbatim
+* localhost
+* localhost:1212
+* 192.168.0.1:1212
+* [::1]:1212
+* @endverbatim
+* Numeric addresses are parsed with ::tcs_address_parse() without any lookup.
+* Without a port, the port of the returned addresses is 0.
+*
+* @param[in] hostname hostname or IP string to resolve, optionally with a port.
 * @param[in] address_family address family filter, or ::TCS_FAMILY_ANY for all.
 * @param[out] out_addresses array to receive resolved addresses, or NULL to only count.
 * @param[in] addresses_length number of elements in the @p out_addresses array.
diff --git a/src/tinycsocket_posix.c b/src/tinycsocket_posix.c
index c6b089d..e34e7a0 100644
--- a/src/tinycsocket_posix.c
+++ b/src/tinycsocket_posix.c
@@ -1707,6 +1707,35 @@ TcsResult tcs_address_resolve(const char* hostname,
     if (address_family.native == -1) // sentinel for unsupported families (e.g. TCS_FAMILY_PACKET on non-Linux)
         return TCS_ERROR_NOT_SUPPORTED;
 
+    // getaddrinfo() does not understand "hostname:port". A string with exactly one ':' carries a port, which is
+    // split off here and applied to the results. Brackets belong to numeric IPv6 only, handled by the fast path.
+    if (strpbrk(hostname, "[]") != NULL)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    char host[256]; // Hostnames are at most 253 characters
+    uint16_t port = 0;
+    const char* colon = strchr(hostname, ':');
+    bool has_port = colon != NULL && strchr(colon + 1, ':') == NULL;
+    size_t host_size = has_port ? (size_t)(colon - hostname) : strlen(hostname);
+    if (host_size == 0 || host_size >= sizeof host)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (has_port)
+    {
+        if (colon[1] == '\0')
+            return TCS_ERROR_INVALID_ARGUMENT;
+        unsigned long port_value = 0;
+        for (const char* c = colon + 1; *c != '\0'; ++c)
+        {
+            if (*c < '0' || *c > '9')
+                return TCS_ERROR_INVALID_ARGUMENT;
+            port_value = port_value * 10 + (unsigned long)(*c - '0');
+            if (port_value > 65535)
+                return TCS_ERROR_INVALID_ARGUMENT;
+        }
+        port = (uint16_t)port_value;
+    }
+    memcpy(host, hostname, host_size);
+    host[host_size] = '\0';
+
     struct addrinfo native_hints;
     memset(&native_hints, 0, sizeof native_hints);
     native_hints.ai_family = address_family.native;
@@ -1715,7 +1744,7 @@ TcsResult tcs_address_resolve(const char* hostname,
     native_hints.ai_protocol = IPPROTO_UDP;
 
     struct addrinfo* native_addrinfo_list = NULL;
-    int sts = getaddrinfo(hostname, NULL, &native_hints, &native_addrinfo_list);
+    int sts = getaddrinfo(host, NULL, &native_hints, &native_addrinfo_list);
 
     // TODO: Move error codes to errno2retcode()
     if (sts == EAI_SYSTEM)
@@ -1754,6 +1783,10 @@ TcsResult tcs_address_resolve(const char* hostname,
             TcsResult convert_address_status = native2sockaddr(iter->ai_addr, &out_addresses[i]);
             if (convert_address_status != TCS_SUCCESS)
                 continue;
+            if (out_addresses[i].family.native == TCS_FAMILY_IPV4.native)
+                out_addresses[i].data.ipv4.port = port;
+            else if (out_addresses[i].family.native == TCS_FAMILY_IPV6.native)
+                out_addresses[i].data.ipv6.port = port;
             i++;
         }
     }
diff --git a/src/tinycsocket_win32.c b/src/tinycsocket_win32.c
index 80cb7de..d9a8480 100644
--- a/src/tinycsocket_win32.c
+++ b/src/tinycsocket_win32.c
@@ -2545,12 +2545,41 @@ TcsResult tcs_address_resolve(const char* hostname,
     if (address_family.native == TCS_FAMILY_PACKET.native) // Only the numeric fast path above can give a MAC address
         return TCS_ERROR_NOT_SUPPORTED;
 
+    // getaddrinfo() does not understand "hostname:port". A string with exactly one ':' carries a port, which is
+    // split off here and applied to the results. Brackets belong to numeric IPv6 only, handled by the fast path.
+    if (strpbrk(hostname, "[]") != NULL)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    char host[256]; // Hostnames are at most 253 characters
+    uint16_t port = 0;
+    const char* colon = strchr(hostname, ':');
+    bool has_port = colon != NULL && strchr(colon + 1, ':') == NULL;
+    size_t host_size = has_port ? (size_t)(colon - hostname) : strlen(hostname);
+    if (host_size == 0 || host_size >= sizeof host)
+        return TCS_ERROR_INVALID_ARGUMENT;
+    if (has_port)
+    {
+        if (colon[1] == '\0')
+            return TCS_ERROR_INVALID_ARGUMENT;
+        unsigned long port_value = 0;
+        for (const char* c = colon + 1; *c != '\0'; ++c)
+        {
+            if (*c < '0' || *c > '9')
+                return TCS_ERROR_INVALID_ARGUMENT;
+            port_value = port_value * 10 + (unsigned long)(*c - '0');
+            if (port_value > 65535)
+                return TCS_ERROR_INVALID_ARGUMENT;
+        }
+        port = (uint16_t)port_value;
+    }
+    memcpy(host, hostname, host_size);
+    host[host_size] = '\0';
+
     ADDRINFOA native_hints;
     memset(&native_hints, 0, sizeof native_hints);
     native_hints.ai_family = address_family.native;
 
     PADDRINFOA native_addrinfo_list = NULL;
-    int getaddrinfo_status = getaddrinfo(hostname, NULL, &native_hints, &native_addrinfo_list);
+    int getaddrinfo_status = getaddrinfo(host, NULL, &native_hints, &native_addrinfo_list);
     if (getaddrinfo_status != 0)
         return TCS_ERROR_ADDRESS_LOOKUP_FAILED;
 
@@ -2572,6 +2601,10 @@ TcsResult tcs_address_resolve(const char* hostname,
             TcsResult address_convert_status = native2sockaddr(iter->ai_addr, &out_addresses[i]);
             if (address_convert_status != TCS_SUCCESS)
                 continue;
+            if (out_addresses[i].family.native == TCS_FAMILY_IPV4.native)
+                out_addresses[i].data.ipv4.port = port;
+            else if (out_addresses[i].family.native == TCS_FAMILY_IPV6.native)
+                out_addresses[i].data.ipv6.port = port;
             i++;
         }
     }
diff --git a/tests/tests.cpp b/tests/tests.cpp
index 1564812..dab38dc 100644
--- a/tests/tests.cpp
+++ b/tests/tests.cpp
@@ -784,6 +784,180 @@ TEST_CASE("tcs_socket_tcp_str bind and connect")
     REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
 }
 
+TEST_CASE("tcs_socket_tcp_str hostname with port")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // Given
+    // Both ends are given as "hostname:port" (as in the examples), so they resolve to the same address family.
+    TcsSocket listen_socket = TCS_SOCKET_INVALID;
+    TcsSocket accept_socket = TCS_SOCKET_INVALID;
+    TcsSocket client_socket = TCS_SOCKET_INVALID;
+
+    TcsResult listen_res = tcs_socket_tcp_str(&listen_socket, "localhost:1475", NULL, 0);
+    CHECK(listen_res == TCS_SUCCESS);
+    if (listen_res == TCS_SUCCESS)
+    {
+        // The port from the string must have been used when binding
+        struct TcsAddress bound_address = TCS_ADDRESS_NONE;
+        CHECK(tcs_address_socket_local(listen_socket, &bound_address) == TCS_SUCCESS);
+        if (bound_address.family.native == TCS_FAMILY_IPV6.native)
+            CHECK(bound_address.data.ipv6.port == 1475);
+        else
+            CHECK(bound_address.data.ipv4.port == 1475);
+
+        REQUIRE(tcs_listen(listen_socket, TCS_BACKLOG_MAX) == TCS_SUCCESS);
+
+        // When
+        TcsResult connect_res = tcs_socket_tcp_str(&client_socket, NULL, "localhost:1475", 5000);
+        CHECK(connect_res == TCS_SUCCESS);
+        if (connect_res == TCS_SUCCESS) // Guard: never block in accept if the connect failed
+        {
+            CHECK(tcs_accept(listen_socket, &accept_socket, NULL) == TCS_SUCCESS);
+
+            const uint8_t* send_buffer = (const uint8_t*)"hostname";
+            uint8_t recv_buffer[8] = {0};
+            CHECK(tcs_send(client_socket, send_buffer, 8, TCS_MSG_SENDALL, NULL) == TCS_SUCCESS);
+            CHECK(tcs_receive(accept_socket, recv_buffer, 8, TCS_MSG_WAITALL, NULL) == TCS_SUCCESS);
+
+            // Then
+            CHECK(memcmp(recv_buffer, send_buffer, 8) == 0);
+        }
+        else
+        {
+            CHECK(client_socket == TCS_SOCKET_INVALID);
+        }
+    }
+    else
+    {
+        CHECK(listen_socket == TCS_SOCKET_INVALID);
+    }
+
+    // Clean up
+    if (client_socket != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&client_socket) == TCS_SUCCESS);
+    if (accept_socket != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&accept_socket) == TCS_SUCCESS);
+    if (listen_socket != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&listen_socket) == TCS_SUCCESS);
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
+TEST_CASE("tcs_socket_tcp_str IPv6 bracket notation bind and connect")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // Given
+    TcsSocket listen_socket = TCS_SOCKET_INVALID;
+    TcsSocket accept_socket = TCS_SOCKET_INVALID;
+    TcsSocket client_socket = TCS_SOCKET_INVALID;
+
+    REQUIRE(tcs_socket_tcp_str(&listen_socket, "[::1]:1476", NULL, 0) == TCS_SUCCESS);
+    REQUIRE(tcs_listen(listen_socket, TCS_BACKLOG_MAX) == TCS_SUCCESS);
+
+    // When
+    TcsResult connect_res = tcs_socket_tcp_str(&client_socket, NULL, "[::1]:1476", 5000);
+    CHECK(connect_res == TCS_SUCCESS);
+    if (connect_res == TCS_SUCCESS) // Guard: never block in accept if the connect failed
+    {
+        struct TcsAddress peer_address = TCS_ADDRESS_NONE;
+        CHECK(tcs_accept(listen_socket, &accept_socket, &peer_address) == TCS_SUCCESS);
+        CHECK(peer_address.family.native == TCS_FAMILY_IPV6.native);
+        CHECK(tcs_address_is_loopback(&peer_address));
+
+        const uint8_t* send_buffer = (const uint8_t*)"ipv6";
+        uint8_t recv_buffer[8] = {0};
+        CHECK(tcs_send(client_socket, send_buffer, 4, TCS_MSG_SENDALL, NULL) == TCS_SUCCESS);
+        CHECK(tcs_receive(accept_socket, recv_buffer, 4, TCS_MSG_WAITALL, NULL) == TCS_SUCCESS);
+
+        // Then
+        CHECK(memcmp(recv_buffer, send_buffer, 4) == 0);
+    }
+    else
+    {
+        CHECK(client_socket == TCS_SOCKET_INVALID);
+    }
+
+    // Clean up
+    if (client_socket != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&client_socket) == TCS_SUCCESS);
+    if (accept_socket != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&accept_socket) == TCS_SUCCESS);
+    CHECK(tcs_close(&listen_socket) == TCS_SUCCESS);
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
+TEST_CASE("tcs_socket_tcp_str invalid arguments")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // NULL out_socket
+    CHECK(tcs_socket_tcp_str(NULL, "127.0.0.1:1477", NULL, 0) == TCS_ERROR_INVALID_ARGUMENT);
+
+    // Both addresses NULL
+    TcsSocket socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, NULL, NULL, 0) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // out_socket already holds a socket, it must be left untouched
+    TcsSocket existing = TCS_SOCKET_INVALID;
+    REQUIRE(tcs_socket(&existing, TCS_FAMILY_IPV4, TCS_SOCKET_STREAM, TCS_PROTOCOL_IP_TCP) == TCS_SUCCESS);
+    const TcsSocket existing_copy = existing;
+    CHECK(tcs_socket_tcp_str(&existing, "127.0.0.1:1477", NULL, 0) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(existing == existing_copy);
+    CHECK(tcs_close(&existing) == TCS_SUCCESS);
+
+    // Negative timeout other than TCS_WAIT_INF
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, NULL, "127.0.0.1:1477", -2) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Address that can neither be parsed nor resolved
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, NULL, "not an address", 100) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Port out of range or not numeric
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, "localhost:99999", NULL, 0) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, "localhost:14ab", NULL, 0) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Family mismatch between local and remote
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, "127.0.0.1:1477", "[::1]:1477", 100) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Clean up
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
+TEST_CASE("tcs_socket_tcp_str connect failure leaves socket invalid")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // Connect to a port nobody listens on
+    TcsSocket socket = TCS_SOCKET_INVALID;
+    TcsResult res = tcs_socket_tcp_str(&socket, NULL, "127.0.0.1:1478", 100);
+
+    if (res != TCS_ERROR_TIMED_OUT && res != TCS_ERROR_CONNECTION_REFUSED)
+    {
+        WARN(res == TCS_ERROR_TIMED_OUT);
+        WARN(res == TCS_ERROR_CONNECTION_REFUSED);
+        CHECK((res == TCS_ERROR_TIMED_OUT || res == TCS_ERROR_CONNECTION_REFUSED));
+    }
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Clean up
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
 TEST_CASE("tcs_socket_udp bind and send_to")
 {
     // Setup
@@ -888,6 +1062,169 @@ TEST_CASE("tcs_socket_udp_str bind and send_to")
     REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
 }
 
+TEST_CASE("tcs_socket_udp_str hostname with port")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // Given
+    // Both ends are given as "hostname:port" (as in the examples), so they resolve to the same address family.
+    TcsSocket socket_recv = TCS_SOCKET_INVALID;
+    TcsSocket socket_send = TCS_SOCKET_INVALID;
+
+    TcsResult bind_res = tcs_socket_udp_str(&socket_recv, "localhost:1479", NULL);
+    CHECK(bind_res == TCS_SUCCESS);
+    if (bind_res == TCS_SUCCESS)
+    {
+        // The port from the string must have been used when binding
+        struct TcsAddress bound_address = TCS_ADDRESS_NONE;
+        CHECK(tcs_address_socket_local(socket_recv, &bound_address) == TCS_SUCCESS);
+        if (bound_address.family.native == TCS_FAMILY_IPV6.native)
+            CHECK(bound_address.data.ipv6.port == 1479);
+        else
+            CHECK(bound_address.data.ipv4.port == 1479);
+
+        CHECK(tcs_opt_receive_timeout_set(socket_recv, 5000) == TCS_SUCCESS);
+
+        // When
+        TcsResult connect_res = tcs_socket_udp_str(&socket_send, NULL, "localhost:1479");
+        CHECK(connect_res == TCS_SUCCESS);
+        if (connect_res == TCS_SUCCESS)
+        {
+            const uint8_t* send_buffer = (const uint8_t*)"udp";
+            uint8_t recv_buffer[8] = {0};
+            size_t received = 0;
+            struct TcsAddress source_address = TCS_ADDRESS_NONE;
+            CHECK(tcs_send(socket_send, send_buffer, 3, TCS_FLAG_NONE, NULL) == TCS_SUCCESS);
+            CHECK(tcs_receive_from(socket_recv, recv_buffer, 8, TCS_FLAG_NONE, &source_address, &received) ==
+                  TCS_SUCCESS);
+
+            // Then
+            CHECK(received == 3);
+            CHECK(memcmp(recv_buffer, send_buffer, 3) == 0);
+            CHECK(source_address.family.native == bound_address.family.native);
+            CHECK(tcs_address_is_loopback(&source_address));
+        }
+        else
+        {
+            CHECK(socket_send == TCS_SOCKET_INVALID);
+        }
+    }
+    else
+    {
+        CHECK(socket_recv == TCS_SOCKET_INVALID);
+    }
+
+    // Clean up
+    if (socket_send != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&socket_send) == TCS_SUCCESS);
+    if (socket_recv != TCS_SOCKET_INVALID)
+        CHECK(tcs_close(&socket_recv) == TCS_SUCCESS);
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
+TEST_CASE("tcs_socket_udp_str invalid arguments")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // NULL out_socket
+    CHECK(tcs_socket_udp_str(NULL, "127.0.0.1:1480", NULL) == TCS_ERROR_INVALID_ARGUMENT);
+
+    // Both addresses NULL
+    TcsSocket socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, NULL, NULL) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // out_socket already holds a socket, it must be left untouched
+    TcsSocket existing = TCS_SOCKET_INVALID;
+    REQUIRE(tcs_socket(&existing, TCS_FAMILY_IPV4, TCS_SOCKET_DGRAM, TCS_PROTOCOL_IP_UDP) == TCS_SUCCESS);
+    const TcsSocket existing_copy = existing;
+    CHECK(tcs_socket_udp_str(&existing, "127.0.0.1:1480", NULL) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(existing == existing_copy);
+    CHECK(tcs_close(&existing) == TCS_SUCCESS);
+
+    // Address that can neither be parsed nor resolved
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, "not an address", NULL) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Port out of range or not numeric
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, "localhost:99999", NULL) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, "localhost:14ab", NULL) != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Family mismatch between local and remote
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, "127.0.0.1:1480", "[::1]:1480") != TCS_SUCCESS);
+    CHECK(socket == TCS_SOCKET_INVALID);
+
+    // Clean up
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
+TEST_CASE("Socket presets: remote address needs a port, local address does not")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    // A remote address with port 0 can never be meaningful, reject it up front
+    struct TcsAddress remote_no_port = TCS_ADDRESS_NONE;
+    remote_no_port.family = TCS_FAMILY_IPV4;
+    remote_no_port.data.ipv4.address = TCS_ADDRESS_IPV4_LOOPBACK;
+    remote_no_port.data.ipv4.port = 0;
+
+    TcsSocket socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp(&socket, NULL, &remote_no_port, 100) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    if (socket != TCS_SOCKET_INVALID) // Do not leak the socket while this test is red
+        tcs_close(&socket);
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp(&socket, NULL, &remote_no_port) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    if (socket != TCS_SOCKET_INVALID) // Do not leak the socket while this test is red
+        tcs_close(&socket);
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, NULL, "localhost", 100) == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    if (socket != TCS_SOCKET_INVALID) // Do not leak the socket while this test is red
+        tcs_close(&socket);
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, NULL, "127.0.0.1") == TCS_ERROR_INVALID_ARGUMENT);
+    CHECK(socket == TCS_SOCKET_INVALID);
+    if (socket != TCS_SOCKET_INVALID) // Do not leak the socket while this test is red
+        tcs_close(&socket);
+
+    // A local address without port means "any free port", and the chosen port must be readable afterwards
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_tcp_str(&socket, "localhost", NULL, 0) == TCS_SUCCESS);
+    if (socket != TCS_SOCKET_INVALID)
+    {
+        struct TcsAddress bound_address = TCS_ADDRESS_NONE;
+        CHECK(tcs_address_socket_local(socket, &bound_address) == TCS_SUCCESS);
+        if (bound_address.family.native == TCS_FAMILY_IPV6.native)
+            CHECK(bound_address.data.ipv6.port != 0);
+        else
+            CHECK(bound_address.data.ipv4.port != 0);
+        CHECK(tcs_close(&socket) == TCS_SUCCESS);
+    }
+    socket = TCS_SOCKET_INVALID;
+    CHECK(tcs_socket_udp_str(&socket, "127.0.0.1", NULL) == TCS_SUCCESS);
+    if (socket != TCS_SOCKET_INVALID)
+    {
+        struct TcsAddress bound_address = TCS_ADDRESS_NONE;
+        CHECK(tcs_address_socket_local(socket, &bound_address) == TCS_SUCCESS);
+        CHECK(bound_address.data.ipv4.port != 0);
+        CHECK(tcs_close(&socket) == TCS_SUCCESS);
+    }
+
+    // Clean up
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
 TEST_CASE("tcs_poll simple memory check")
 {
     // Setup
@@ -1134,6 +1471,74 @@ TEST_CASE("Address information count")
     // Clean up
     REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
 }
+TEST_CASE("tcs_address_resolve hostname with port")
+{
+    // Setup
+    REQUIRE(tcs_lib_init() == TCS_SUCCESS);
+
+    struct TcsAddress addresses[4];
+    size_t count = 0;
+
+    // "hostname:port" must resolve and carry the port on every returned address
+    CHECK(tcs_address_resolve("localhost:1212", TCS_FAMILY_ANY, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count > 0);
+    for (size_t i = 0; i < count && i < 4; ++i)
+    {
+        CHECK(tcs_address_is_loopback(&addresses[i]));
+        if (addresses[i].family.native == TCS_FAMILY_IPV6.native)
+            CHECK(addresses[i].data.ipv6.port == 1212);
+        else
+            CHECK(addresses[i].data.ipv4.port == 1212);
+    }
+
+    // Family filter still applies
+    count = 0;
+    CHECK(tcs_address_resolve("localhost:1213", TCS_FAMILY_IPV4, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count > 0);
+    CHECK(addresses[0].family.native == TCS_FAMILY_IPV4.native);
+    CHECK(addresses[0].data.ipv4.address == TCS_ADDRESS_IPV4_LOOPBACK);
+    CHECK(addresses[0].data.ipv4.port == 1213);
+
+    // Counting only (no output array) must work with a port too
+    count = 0;
+    CHECK(tcs_address_resolve("localhost:1212", TCS_FAMILY_ANY, NULL, 0, &count) == TCS_SUCCESS);
+    CHECK(count > 0);
+
+    // Without port the port is 0
+    count = 0;
+    CHECK(tcs_address_resolve("localhost", TCS_FAMILY_IPV4, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count > 0);
+    CHECK(addresses[0].data.ipv4.port == 0);
+
+    // Numeric forms are unchanged: port when given, IPv6 without brackets has no port
+    count = 0;
+    CHECK(tcs_address_resolve("127.0.0.1:80", TCS_FAMILY_ANY, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count == 1);
+    CHECK(addresses[0].family.native == TCS_FAMILY_IPV4.native);
+    CHECK(addresses[0].data.ipv4.port == 80);
+    count = 0;
+    CHECK(tcs_address_resolve("[::1]:443", TCS_FAMILY_ANY, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count == 1);
+    CHECK(addresses[0].family.native == TCS_FAMILY_IPV6.native);
+    CHECK(addresses[0].data.ipv6.port == 443);
+    count = 0;
+    CHECK(tcs_address_resolve("::1", TCS_FAMILY_ANY, addresses, 4, &count) == TCS_SUCCESS);
+    CHECK(count == 1);
+    CHECK(addresses[0].family.native == TCS_FAMILY_IPV6.native);
+    CHECK(addresses[0].data.ipv6.port == 0);
+
+    // Bad ports are rejected
+    count = 0;
+    CHECK(tcs_address_resolve("localhost:99999", TCS_FAMILY_ANY, addresses, 4, &count) != TCS_SUCCESS);
+    count = 0;
+    CHECK(tcs_address_resolve("localhost:14ab", TCS_FAMILY_ANY, addresses, 4, &count) != TCS_SUCCESS);
+    count = 0;
+    CHECK(tcs_address_resolve("localhost:", TCS_FAMILY_ANY, addresses, 4, &count) != TCS_SUCCESS);
+
+    // Clean up
+    REQUIRE(tcs_lib_cleanup() == TCS_SUCCESS);
+}
+
 TEST_CASE("Interface list")
 {
     // Setup