diff --git a/src/qml/Qt6QmlMacros.cmake b/src/qml/Qt6QmlMacros.cmake
index b6899f8e00..0284d0e75f 100644
--- a/src/qml/Qt6QmlMacros.cmake
+++ b/src/qml/Qt6QmlMacros.cmake
@@ -2157,6 +2157,12 @@ function(qt6_target_qml_sources target)
                 get_source_file_property(qml_file_singleton ${qml_file_src} QT_QML_SINGLETON_TYPE)
                 get_source_file_property(qml_file_internal  ${qml_file_src} QT_QML_INTERNAL_TYPE)
 
+                if (qml_file_singleton AND qml_file_internal)
+                   message(FATAL_ERROR
+                       "${qml_file_src} is marked as both internal and as a "
+                       "singleton, but singletons cannot be internal!")
+                endif()
+
                 if (NOT qml_file_versions)
                     set(qml_file_versions ${qml_module_files_versions})
                 endif()
diff --git a/tests/auto/cmake/CMakeLists.txt b/tests/auto/cmake/CMakeLists.txt
index fd2053176a..606a743bbb 100644
--- a/tests/auto/cmake/CMakeLists.txt
+++ b/tests/auto/cmake/CMakeLists.txt
@@ -110,6 +110,7 @@ if(TARGET Qt::Qml)
     If(NOT ANDROID) # QML only project cannot run on Android with C++ enty point
         _qt_internal_test_expect_pass(qmlquery)
     endif()
+    _qt_internal_test_expect_fail(test_internal_singleton)
 endif()
 
 if(TARGET Qt::Quick)
diff --git a/tests/auto/cmake/test_internal_singleton/CMakeLists.txt b/tests/auto/cmake/test_internal_singleton/CMakeLists.txt
new file mode 100644
index 0000000000..f1db46a0f9
--- /dev/null
+++ b/tests/auto/cmake/test_internal_singleton/CMakeLists.txt
@@ -0,0 +1,23 @@
+# Copyright (C) 2023 The Qt Company Ltd.
+# SPDX-License-Identifier: BSD-3-Clause
+
+
+cmake_minimum_required(VERSION 3.19)
+
+project(test_internal_singleton)
+
+find_package(Qt6 REQUIRED COMPONENTS Qml)
+
+qt_standard_project_setup()
+
+set_source_files_properties(Test.qml PROPERTIES
+    QT_QML_SINGLETON_TYPE TRUE
+    QT_QML_INTERNAL_TYPE TRUE
+)
+
+qt_add_qml_module(test_internal_singleton
+    URI Controls
+    VERSION 1.0
+    QML_FILES
+    Test.qml
+)
diff --git a/tests/auto/cmake/test_internal_singleton/Test.qml b/tests/auto/cmake/test_internal_singleton/Test.qml
new file mode 100644
index 0000000000..a2eb03bd4e
--- /dev/null
+++ b/tests/auto/cmake/test_internal_singleton/Test.qml
@@ -0,0 +1,4 @@
+pragma singleton
+import QtQml
+
+QtObject {}