diff --git a/sys/os2/os2.c b/sys/os2/os2.c
index cf37dc77d..676774ebd 100644
--- a/sys/os2/os2.c
+++ b/sys/os2/os2.c
@@ -358,4 +358,7 @@ int *lan_username_size;
 {
   return (char*)0;
 }
+#ifdef X11_GRAPHICS
+int errno;
+#endif
 #endif /* OS2 */