diff --git a/backends/kwayland/waylandconfig.cpp b/backends/kwayland/waylandconfig.cpp
--- a/backends/kwayland/waylandconfig.cpp
+++ b/backends/kwayland/waylandconfig.cpp
@@ -245,7 +245,8 @@
     }
 
     // remove the output from output mapping
-    Q_ASSERT(m_outputMap.take(output->id()) == output);
+    const auto removedOutput = m_outputMap.take(output->id());
+    Q_ASSERT(removedOutput == output); Q_UNUSED(removedOutput);
     m_screen->setOutputs(m_outputMap.values());
     delete output;