diff --git a/composite.cpp b/composite.cpp
index 683b5a5641..cdf5d65f7e 100644
--- a/composite.cpp
+++ b/composite.cpp
@@ -886,7 +886,6 @@ X11Compositor::X11Compositor(QObject *parent)
     , m_suspended(options->isUseCompositing() ? NoReasonSuspend : UserSuspend)
     , m_xrrRefreshRate(0)
 {
-    qRegisterMetaType<X11Compositor::SuspendReason>("X11Compositor::SuspendReason");
 }
 
 void X11Compositor::toggleCompositing()
@@ -1015,25 +1014,27 @@ void X11Compositor::updateClientCompositeBlocking(X11Client *c)
         if (c->isBlockingCompositing()) {
             // Do NOT attempt to call suspend(true) from within the eventchain!
             if (!(m_suspended & BlockRuleSuspend))
-                QMetaObject::invokeMethod(this, "suspend", Qt::QueuedConnection,
-                                          Q_ARG(SuspendReason, BlockRuleSuspend));
+                QMetaObject::invokeMethod(this, [this]() {
+                        suspend(BlockRuleSuspend);
+                    }, Qt::QueuedConnection);
         }
     }
     else if (m_suspended & BlockRuleSuspend) {
         // If !c we just check if we can resume in case a blocking client was lost.
-        bool resume = true;
+        bool shouldResume = true;
 
         for (ClientList::ConstIterator it = Workspace::self()->clientList().constBegin();
              it != Workspace::self()->clientList().constEnd(); ++it) {
             if ((*it)->isBlockingCompositing()) {
-                resume = false;
+                shouldResume = false;
                 break;
             }
         }
-        if (resume) {
+        if (shouldResume) {
             // Do NOT attempt to call suspend(false) from within the eventchain!
-            QMetaObject::invokeMethod(this, "resume", Qt::QueuedConnection,
-                                      Q_ARG(SuspendReason, BlockRuleSuspend));
+                QMetaObject::invokeMethod(this, [this]() {
+                        resume(BlockRuleSuspend);
+                    }, Qt::QueuedConnection);
         }
     }
 }
diff --git a/composite.h b/composite.h
index 62825ea19b..84783c8316 100644
--- a/composite.h
+++ b/composite.h
@@ -201,6 +201,8 @@ public:
         AllReasonSuspend    = 0xff
     };
     Q_DECLARE_FLAGS(SuspendReasons, SuspendReason)
+    Q_ENUM(SuspendReason)
+    Q_FLAG(SuspendReasons)
 
     static X11Compositor *create(QObject *parent = nullptr);
 
@@ -214,7 +216,7 @@ public:
      * @see resume
      * @see isActive
      */
-    Q_INVOKABLE void suspend(SuspendReason reason);
+    void suspend(SuspendReason reason);
 
     /**
      * @brief Resumes the Compositor if it is currently suspended.
@@ -233,7 +235,7 @@ public:
      * @see isCompositingPossible
      * @see isOpenGLBroken
      */
-    Q_INVOKABLE void resume(SuspendReason reason);
+    void resume(SuspendReason reason);
 
     void toggleCompositing() override;
     void reinitialize() override;
diff --git a/plugins/scenes/opengl/scene_opengl.cpp b/plugins/scenes/opengl/scene_opengl.cpp
index 325a590fe0..dfca31f3ad 100644
--- a/plugins/scenes/opengl/scene_opengl.cpp
+++ b/plugins/scenes/opengl/scene_opengl.cpp
@@ -830,8 +830,10 @@ bool SceneOpenGL::viewportLimitsMatched(const QSize &size) const {
     GLint limit[2];
     glGetIntegerv(GL_MAX_VIEWPORT_DIMS, limit);
     if (limit[0] < size.width() || limit[1] < size.height()) {
-        QMetaObject::invokeMethod(static_cast<X11Compositor*>(Compositor::self()), "suspend",
-                                  Qt::QueuedConnection, Q_ARG(X11Compositor::SuspendReason, X11Compositor::AllReasonSuspend));
+        auto compositor = static_cast<X11Compositor*>(Compositor::self());
+        QMetaObject::invokeMethod(compositor, [compositor]() {
+                compositor->suspend(X11Compositor::AllReasonSuspend);
+            }, Qt::QueuedConnection);
         return false;
     }
     return true;