diff --git a/js/src/jsnum.h b/js/src/jsnum.h
index e3e02fc5d12a..4748dc99f86b 100644
--- a/js/src/jsnum.h
+++ b/js/src/jsnum.h
@@ -69,7 +69,7 @@ typedef union jsdpun {
         uint32 hi, lo;
 #endif
     } s;
-    JSUint64 u64;
+    uint64   u64;
     jsdouble d;
 } jsdpun;