diff --git a/src/gtk/window.cpp b/src/gtk/window.cpp
index d57145134e..854937fed3 100644
--- a/src/gtk/window.cpp
+++ b/src/gtk/window.cpp
@@ -755,10 +755,10 @@ wxTranslateGTKKeyEventToWx(wxKeyEvent& event,
 
     KeySym keysym = gdk_event->keyval;
 
-    wxLogTrace(TRACE_KEYS, wxT("Key %s event: keysym = %ld"),
+    wxLogTrace(TRACE_KEYS, wxT("Key %s event: keysym = %lu"),
                event.GetEventType() == wxEVT_KEY_UP ? wxT("release")
                                                     : wxT("press"),
-               keysym);
+               static_cast<unsigned long>(keysym));
 
     long key_code = wxTranslateKeySymToWXKey(keysym, false /* !isChar */);