diff --git a/modules/libpref/public/nsIPref.h b/modules/libpref/public/nsIPref.h
index 6e9a8be30b6..e402c611230 100644
--- a/modules/libpref/public/nsIPref.h
+++ b/modules/libpref/public/nsIPref.h
@@ -58,7 +58,7 @@ typedef int (*PrefChangedFunc) (const char *, void *);
 class nsIPref: public nsISupports {
 public:
 
-  static const nsIID& GetIID(void) { static nsIID iid = NS_IPREF_IID; return iid; }
+  NS_DEFINE_STATIC_IID_ACCESSOR(NS_IPREF_IID)
 
   // Initialize/shutdown
   NS_IMETHOD Startup(char *filename) = 0;