diff --git a/mozilla/modules/plugin/samples/default/os2/plugin.cpp b/mozilla/modules/plugin/samples/default/os2/plugin.cpp
index ac40b0012a7..d24f27ec9e5 100644
--- a/mozilla/modules/plugin/samples/default/os2/plugin.cpp
+++ b/mozilla/modules/plugin/samples/default/os2/plugin.cpp
@@ -39,6 +39,7 @@
 #define INCL_WIN
 #include <os2.h>
 #include <assert.h>
+#include <stdio.h>
 
 #include "npnulos2.h"