diff --git a/globals.c b/globals.c
index ee6417b..811160f 100644
--- a/globals.c
+++ b/globals.c
@@ -46,7 +46,8 @@
 
 void xmlCleanupGlobals()
 {
-    xmlFreeMutex(xmlThrDefMutex);
+    if (xmlThrDefMutex != NULL)
+	xmlFreeMutex(xmlThrDefMutex);
 }
 
 /************************************************************************