diff --git a/src/Main/WindowSystemAdapter.cxx b/src/Main/WindowSystemAdapter.cxx
index 14530b5bb..2739cd045 100644
--- a/src/Main/WindowSystemAdapter.cxx
+++ b/src/Main/WindowSystemAdapter.cxx
@@ -111,7 +111,7 @@ void WindowSystemAdapter::puGetWindowSize(int* width, int* height)
     *height = traits->height;
 }
 
-bool WindowSystemAdapter::puInitialize()
+void WindowSystemAdapter::puInitialize()
 {
     puSetWindowFuncs(puGetWindow, 0, puGetWindowSize, 0);
     puRealInit();
diff --git a/src/Main/WindowSystemAdapter.hxx b/src/Main/WindowSystemAdapter.hxx
index 5fe805278..8683632b3 100644
--- a/src/Main/WindowSystemAdapter.hxx
+++ b/src/Main/WindowSystemAdapter.hxx
@@ -119,7 +119,7 @@ public:
     /** Initialize the plib pui interface library. This might happen
      *in another thread and may be deferred.
      */
-    virtual bool puInitialize();
+    virtual void puInitialize();
     /** Returns true if pui initialization has finished.
      */
     template<typename T>