diff --git a/cmake/QtInternalTargets.cmake b/cmake/QtInternalTargets.cmake
index 50cebbf342a..c53df7e6bfe 100644
--- a/cmake/QtInternalTargets.cmake
+++ b/cmake/QtInternalTargets.cmake
@@ -156,6 +156,7 @@ qt_internal_add_global_definition(QT_NO_NARROWING_CONVERSIONS_IN_CONNECT)
 qt_internal_add_global_definition(QT_EXPLICIT_QFILE_CONSTRUCTION_FROM_PATH)
 qt_internal_add_global_definition(QT_USE_QSTRINGBUILDER SCOPE PLUGIN TOOL MODULE)
 qt_internal_add_global_definition(QT_NO_FOREACH)
+qt_internal_add_global_definition(QT_NO_STD_FORMAT_SUPPORT SCOPE PLUGIN TOOL MODULE)
 
 if(WARNINGS_ARE_ERRORS)
     qt_internal_set_warnings_are_errors_flags(PlatformModuleInternal INTERFACE)
diff --git a/src/corelib/io/qtformat_impl.h b/src/corelib/io/qtformat_impl.h
index 31031324ae6..648d0a9afe2 100644
--- a/src/corelib/io/qtformat_impl.h
+++ b/src/corelib/io/qtformat_impl.h
@@ -12,11 +12,22 @@
 #include <QtCore/qsystemdetection.h>
 #include <QtCore/qtconfigmacros.h>
 
+// Users can disable std::format support in their
+// projects by using this definition.
+#ifndef QT_NO_STD_FORMAT_SUPPORT
+
 #if (defined(__cpp_lib_format) && (__cpp_lib_format >= 202106L))
 
 #include <format>
+// If this macro is defined, std::format support is actually available.
+// Use it to provide the implementation!
+// Note that any out-of-line helper function should not depend on this
+// definition, as it should be unconditionally available even in C++17 builds
+// to keep BC.
 #define QT_SUPPORTS_STD_FORMAT  1
 
 #endif // __cpp_lib_format
 
+#endif // QT_NO_STD_FORMAT_SUPPORT
+
 #endif // QTFORMAT_IMPL_H