diff --git a/Mac/mwerks/mwerks_small_config.h b/Mac/mwerks/mwerks_small_config.h
index 37d2982cd2e..5b99aa5dbec 100644
--- a/Mac/mwerks/mwerks_small_config.h
+++ b/Mac/mwerks/mwerks_small_config.h
@@ -33,3 +33,8 @@
 #define MSL_USE_PRECOMPILED_HEADERS 0	/* Don't use precomp headers: we include our own */
 #include <ansi_prefix.mac.h>
 #endif
+/* Missing declarations. Should these go to pyport.h? */
+#ifdef USE_GUSI2
+#include <stdio.h>
+extern int fileno(FILE *);
+#endif