diff --git a/Modules/errnomodule.c b/Modules/errnomodule.c
index aef671c..f23e27f 100644
--- a/Modules/errnomodule.c
+++ b/Modules/errnomodule.c
@@ -33,6 +33,11 @@
 
 #include "Python.h"
 
+/* Mac with GUSI has more errors than those in errno.h */
+#ifdef USE_GUSI
+#include <sys/errno.h>
+#endif
+
 /*
  * Pull in the system error definitions
  */