diff --git a/mozilla/embedding/base/nsEmbedAPI.h b/mozilla/embedding/base/nsEmbedAPI.h
index 3566cd64ea1..13f835aa086 100644
--- a/mozilla/embedding/base/nsEmbedAPI.h
+++ b/mozilla/embedding/base/nsEmbedAPI.h
@@ -106,7 +106,7 @@ typedef MSG nsEmbedNativeEvent;
 #endif
 
 /* OS/2 specific stuff */
-#ifdef OS2
+#ifdef XP_OS2
 #include "os2.h"
 
 /**