diff --git a/mozilla/xpcom/base/nsID.h b/mozilla/xpcom/base/nsID.h
index e11aea756b6..45f5ca058a5 100644
--- a/mozilla/xpcom/base/nsID.h
+++ b/mozilla/xpcom/base/nsID.h
@@ -72,7 +72,15 @@ struct nsID {
    */
 
   inline PRBool Equals(const nsID& other) const {
+#ifdef XP_UNIX
+    return (PRBool)
+      ((((PRUint32*) &m0)[0] == ((PRUint32*) &other.m0)[0]) &&
+       (((PRUint32*) &m0)[1] == ((PRUint32*) &other.m0)[1]) &&
+       (((PRUint32*) &m0)[2] == ((PRUint32*) &other.m0)[2]) &&
+       (((PRUint32*) &m0)[3] == ((PRUint32*) &other.m0)[3]));
+#else
     return (memcmp(this, &other, sizeof(*this)) == 0);
+#endif
   }
 
   /**