diff --git a/src/plugins/debugger/dap/dapengine.h b/src/plugins/debugger/dap/dapengine.h
index 52b84a36a6f..6f0ae730c17 100644
--- a/src/plugins/debugger/dap/dapengine.h
+++ b/src/plugins/debugger/dap/dapengine.h
@@ -35,7 +35,7 @@ public:
     void handleNext();
 
     VariableItem currentItem() const { return m_currentVarItem; }
-    int queueSize() const { return m_queue.size(); }
+    int queueSize() const { return int(m_queue.size()); }
 
 private:
     void startHandling();