diff --git a/src/motif/app.cpp b/src/motif/app.cpp
index 3fcf24b910..1e62d38bda 100644
--- a/src/motif/app.cpp
+++ b/src/motif/app.cpp
@@ -126,7 +126,9 @@ void wxApp::CleanUp()
     // create a module for that as it's part of the core.
 #if wxUSE_THREADS
     delete wxPendingEvents;
+    wxPendingEvents = NULL;
     delete wxPendingEventsLocker;
+    wxPendingEventsLocker = NULL;
 #endif
 
 #if (defined(__WXDEBUG__) && wxUSE_MEMORY_TRACING) || wxUSE_DEBUG_CONTEXT