diff --git a/mozilla/modules/libutil/public/stopwatch.h b/mozilla/modules/libutil/public/stopwatch.h
index 69c0c227c53..4a45f64801f 100644
--- a/mozilla/modules/libutil/public/stopwatch.h
+++ b/mozilla/modules/libutil/public/stopwatch.h
@@ -4,6 +4,8 @@
 #include "nscore.h"
 #include "prlog.h"
 #include "nsDeque.h"
+#undef printf
+#undef fprintf
 
 #ifdef XP_MAC
 #define R__MAC