diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0daf215f14..70a3ff73f9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -4,7 +4,7 @@ project(KWin)
 set(PROJECT_VERSION "5.18.80")
 set(PROJECT_VERSION_MAJOR 5)
 
-set(QT_MIN_VERSION "5.14.0")
+set(QT_MIN_VERSION "5.12.0")
 set(KF5_MIN_VERSION "5.66.0")
 
 set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/modules ${CMAKE_MODULE_PATH})
diff --git a/wayland_server.cpp b/wayland_server.cpp
index ade32fc8f6..fa53d3e82b 100644
--- a/wayland_server.cpp
+++ b/wayland_server.cpp
@@ -731,7 +731,11 @@ quint32 WaylandServer::createWindowId(SurfaceInterface *surface)
 
 quint16 WaylandServer::createClientId(ClientConnection *c)
 {
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 14, 0))
     const QSet<unsigned short> ids(m_clientIds.constBegin(), m_clientIds.constEnd());
+#else
+    const auto ids = m_clientIds.toSet();
+#endif
     quint16 id = 1;
     if (!ids.isEmpty()) {
         for (quint16 i = ids.count() + 1; i >= 1 ; i--) {