diff --git a/io/io/inc/ROOT/RFile.hxx b/io/io/inc/ROOT/RFile.hxx
index c3d7fe8637270..9b2000e01abd2 100644
--- a/io/io/inc/ROOT/RFile.hxx
+++ b/io/io/inc/ROOT/RFile.hxx
@@ -381,6 +381,9 @@ public:
    /// Puts object `namedObj` in the file under the path `dirPath/namedObj.GetName()`, giving it a title equal to
    /// `namedObj.GetTitle()`.
    /// If `dirPath` is empty (default), the object is put at the top level of the file.
+   ///
+   /// \throws ROOT::RException if `dirPath/namedObj.GetName()` results in an invalid object path. Notably, this
+   /// includes the case where `namedObj.GetName()` contains a slash character.
    void Put(const class TNamed &namedObj, std::string_view dirPath = "");
 
    /// Puts an object into the file, overwriting any previously-existing object at that path.
diff --git a/io/io/src/RFile.cxx b/io/io/src/RFile.cxx
index 15e6d786732a3..09843058bff76 100644
--- a/io/io/src/RFile.cxx
+++ b/io/io/src/RFile.cxx
@@ -331,6 +331,10 @@ void *RFile::GetUntyped(std::string_view path,
 
 void RFile::Put(const TNamed &namedObj, std::string_view dirPath)
 {
+   if (strchr(namedObj.GetName(), '/')) {
+      throw ROOT::RException(R__FAIL(std::string("TNamed object '") + namedObj.GetName() +
+                                     "' given to RFile::Put cannot have '/' in its name!"));
+   }
    std::string completePath = (dirPath.empty() ? "" : std::string(dirPath) + '/') + namedObj.GetName();
    Put(completePath, namedObj, namedObj.GetTitle());
 }
diff --git a/io/io/test/rfile.cxx b/io/io/test/rfile.cxx
index 410b25b40fa9b..8f6793aacc62a 100644
--- a/io/io/test/rfile.cxx
+++ b/io/io/test/rfile.cxx
@@ -931,3 +931,39 @@ TEST(RFile, PutTNamed)
       EXPECT_EQ(key2.GetTitle(), "title 2");
    }
 }
+
+TEST(RFile, PutTNamedInvalid)
+{
+   FileRaii fileGuard("test_rfile_put_tnamed_invalid.root");
+
+   {
+      TNamed named1("my/funny/name", "title 1");
+      TNamed named2("", "title 2");
+      TNamed named3("invalid.name", "title 3");
+      auto file = RFile::Recreate(fileGuard.GetPath());
+      try {
+         file->Put(named1);
+         FAIL() << "putting objects with a slash in their name should fail.";
+      } catch (const ROOT::RException &ex) {
+         EXPECT_THAT(ex.what(), testing::HasSubstr("cannot have '/'"));
+      }
+      try {
+         file->Put(named2, "my/dir");
+         FAIL() << "putting objects with an empty name should fail.";
+      } catch (const ROOT::RException &ex) {
+         EXPECT_THAT(ex.what(), testing::HasSubstr("Invalid object path"));
+      }
+      try {
+         file->Put(named2);
+         FAIL() << "putting objects with an empty name should fail.";
+      } catch (const ROOT::RException &ex) {
+         EXPECT_THAT(ex.what(), testing::HasSubstr("Invalid object path"));
+      }
+      try {
+         file->Put(named3);
+         FAIL() << "putting objects with an invalid name should fail.";
+      } catch (const ROOT::RException &ex) {
+         EXPECT_THAT(ex.what(), testing::HasSubstr("Invalid object path"));
+      }
+   }
+}