diff --git a/mozilla/toolkit/xre/nsUpdateDriver.cpp b/mozilla/toolkit/xre/nsUpdateDriver.cpp
index 5816fcb6122..9f3680055bf 100644
--- a/mozilla/toolkit/xre/nsUpdateDriver.cpp
+++ b/mozilla/toolkit/xre/nsUpdateDriver.cpp
@@ -54,7 +54,7 @@
 # include <direct.h>
 # include <process.h>
 # include <windows.h>
-#elif defined(XP_UNIX)
+#elif defined(XP_UNIX) || defined(XP_OS2)
 # include <unistd.h>
 #endif