diff --git a/TestConcoreHpp.cpp b/TestConcoreHpp.cpp
index 6b6ad2c..f7311af 100644
--- a/TestConcoreHpp.cpp
+++ b/TestConcoreHpp.cpp
@@ -333,7 +333,7 @@ static void test_load_params_semicolon_format() {
 
 static void test_tryparam_comma_in_value() {
     setup_dirs();
-    write_file("in/1/concore.params", "{'channels': [1, 2], 'gain': '0.5'}");
+    write_file("in1/concore.params", "{'channels': [1, 2], 'gain': '0.5'}");
 
     Concore c;
     c.delay = 0;
@@ -342,7 +342,7 @@ static void test_tryparam_comma_in_value() {
     check("tryparam preserves list with comma", c.tryparam("channels", "") == "[1, 2]");
     check("tryparam preserves subsequent key",  c.tryparam("gain", "") == "0.5");
 
-    rm("in/1/concore.params");
+    rm("in1/concore.params");
 }
 
 // ------------- main -------------------------------------------------------
diff --git a/concore.jl b/concore.jl
index af47901..1d6f5d3 100644
--- a/concore.jl
+++ b/concore.jl
@@ -274,10 +274,11 @@ function _zmq_read(port_name::AbstractString, initstr::AbstractString)::Vector{F
     port = get(zmq_ports, String(port_name), nothing)
     port === nothing && error("ZMQ port '$port_name' not registered")
 
-    global simtime
+    global s, simtime
     _apply_write()
     try
         msg = _zmq_recv(port.socket)
+        s = _cap_s(s, msg)
         vals = safe_parse_list(msg)
         simtime = max(simtime, vals[1])
         return vals[2:end]
diff --git a/concoredocker.jl b/concoredocker.jl
index e2c03c1..39d087a 100644
--- a/concoredocker.jl
+++ b/concoredocker.jl
@@ -275,10 +275,11 @@ function _zmq_read(port_name::AbstractString, initstr::AbstractString)::Vector{F
     port = get(zmq_ports, String(port_name), nothing)
     port === nothing && error("ZMQ port '$port_name' not registered")
 
-    global simtime
+    global s, simtime
     _apply_write()
     try
         msg = _zmq_recv(port.socket)
+        s = _cap_s(s, msg)
         vals = safe_parse_list(msg)
         simtime = max(simtime, vals[1])
         return vals[2:end]
diff --git a/tests/julia/test_concoredocker.jl b/tests/julia/test_concoredocker.jl
index fbb2724..147380a 100644
--- a/tests/julia/test_concoredocker.jl
+++ b/tests/julia/test_concoredocker.jl
@@ -82,4 +82,26 @@ const DockerConcore = DockerRuntime.Concore
         end
     end
 
+    if DockerConcore.HAS_ZMQ
+        @testset "ZMQ read updates unchanged" begin
+            using Sockets
+
+            reset_docker_state!()
+            server = Sockets.listen(Sockets.localhost, 0)
+            tcp_port = Sockets.getsockname(server)[2]
+            close(server)
+            address = "tcp://127.0.0.1:$tcp_port"
+
+            DockerConcore.init_zmq_port("out", "bind", address, "PAIR")
+            DockerConcore.init_zmq_port("in", "connect", address, "PAIR")
+            sleep(0.1)
+
+            DockerConcore.concore_write("out", "signal", [10.0])
+            @test DockerConcore.unchanged()
+            @test DockerConcore.concore_read("in", "signal", "[0.0, 0.0]") == [10.0]
+            @test !DockerConcore.unchanged()
+            DockerConcore.terminate_zmq()
+        end
+    end
+
 end
\ No newline at end of file
diff --git a/tests/julia/test_zmq.jl b/tests/julia/test_zmq.jl
index ba9fe3d..0b3ac85 100644
--- a/tests/julia/test_zmq.jl
+++ b/tests/julia/test_zmq.jl
@@ -97,6 +97,24 @@
             @test Concore.simtime == 4.0
             reset_zmq_state!()
         end
+
+        @testset "ZMQ read updates unchanged" begin
+            reset_zmq_state!()
+            server = Sockets.listen(Sockets.localhost, 0)
+            tcp_port = Sockets.getsockname(server)[2]
+            close(server)
+            address = "tcp://127.0.0.1:$tcp_port"
+
+            Concore.init_zmq_port("out", "bind", address, "PAIR")
+            Concore.init_zmq_port("in", "connect", address, "PAIR")
+            sleep(0.1)
+
+            Concore.concore_write("out", "signal", [10.0])
+            @test Concore.unchanged()
+            @test Concore.concore_read("in", "signal", "[0.0, 0.0]") == [10.0]
+            @test !Concore.unchanged()
+            reset_zmq_state!()
+        end
     else
         @testset "live ZMQ skipped" begin
             @test_skip "ZMQ.jl not installed"