diff --git a/mozilla/webshell/tests/viewer/nsViewerApp.cpp b/mozilla/webshell/tests/viewer/nsViewerApp.cpp
index a5f86faa607..12233325fb1 100644
--- a/mozilla/webshell/tests/viewer/nsViewerApp.cpp
+++ b/mozilla/webshell/tests/viewer/nsViewerApp.cpp
@@ -516,8 +516,10 @@ nsViewerApp::AfterDispatch()
 #include "nsIURL.h"
 
 #ifndef XP_PC
+#ifndef XP_MAC
 #define _MAX_PATH 512
 #endif
+#endif
 
 #define DEBUG_EMPTY "(none)"
 static PRInt32 gDebugRobotLoads = 5000;