diff --git a/include/wx/x11/app.h b/include/wx/x11/app.h
index f770198fc6..77927b4f49 100644
--- a/include/wx/x11/app.h
+++ b/include/wx/x11/app.h
@@ -75,7 +75,7 @@ public:
     virtual bool ProcessXEvent(WXEvent* event);
     
 #ifdef __WXDEBUG__
-    virtual void OnAssert(const wxChar *file, int line, const wxChar *msg);
+    virtual void OnAssert(const wxChar *file, int line, const wxChar* cond, const wxChar *msg);
 #endif // __WXDEBUG__
     
 protected:
diff --git a/src/x11/app.cpp b/src/x11/app.cpp
index a1eb5192b5..42749948e2 100644
--- a/src/x11/app.cpp
+++ b/src/x11/app.cpp
@@ -1221,12 +1221,12 @@ bool wxApp::Yield(bool onlyIfNeeded)
 
 #ifdef __WXDEBUG__
 
-void wxApp::OnAssert(const wxChar *file, int line, const wxChar *msg)
+void wxApp::OnAssert(const wxChar *file, int line, const wxChar* cond, const wxChar *msg)
 {
     // While the GUI isn't working that well, just print out the
     // message.
 #if 1
-    wxAppBase::OnAssert(file, line, msg);
+    wxAppBase::OnAssert(file, line, cond, msg);
 #else
     wxString msg2;
     msg2.Printf("At file %s:%d: %s", file, line, msg);