diff --git a/mozilla/xpcom/io/nsAppFileLocationProvider.cpp b/mozilla/xpcom/io/nsAppFileLocationProvider.cpp
index d63aaa4a06e..88e660300a3 100755
--- a/mozilla/xpcom/io/nsAppFileLocationProvider.cpp
+++ b/mozilla/xpcom/io/nsAppFileLocationProvider.cpp
@@ -112,7 +112,7 @@ nsAppFileLocationProvider::~nsAppFileLocationProvider()
 // nsAppFileLocationProvider::nsISupports
 //*****************************************************************************   
 
-NS_IMPL_ISUPPORTS1(nsAppFileLocationProvider, nsIDirectoryServiceProvider)
+NS_IMPL_THREADSAFE_ISUPPORTS1(nsAppFileLocationProvider, nsIDirectoryServiceProvider)
 
 //*****************************************************************************
 // nsAppFileLocationProvider::nsIDirectoryServiceProvider