diff --git a/mozilla/modules/plugin/samples/default/windows/npshell.cpp b/mozilla/modules/plugin/samples/default/windows/npshell.cpp
index b936030af65..a311ec115ef 100644
--- a/mozilla/modules/plugin/samples/default/windows/npshell.cpp
+++ b/mozilla/modules/plugin/samples/default/windows/npshell.cpp
@@ -103,7 +103,8 @@ NPError NP_LOADDS NPP_New(NPMIMEType pluginType,
   if(buf != NULL)
   {
     buf = strrchr(buf, '.');
-    szFileExtension = ++buf;
+    if(buf)
+      szFileExtension = ++buf;
   }
 
   CPlugin * pPlugin = new CPlugin(hInst,