diff --git a/Include/sysmodule.h b/Include/sysmodule.h
index 36a4499..f6e4d08 100644
--- a/Include/sysmodule.h
+++ b/Include/sysmodule.h
@@ -1,3 +1,9 @@
+#ifndef Py_SYSMODULE_H
+#define Py_SYSMODULE_H
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 /***********************************************************
 Copyright 1991, 1992, 1993 by Stichting Mathematisch Centrum,
 Amsterdam, The Netherlands.
@@ -30,3 +36,8 @@
 void initsys PROTO((void));
 
 extern object *sys_trace, *sys_profile;
+
+#ifdef __cplusplus
+}
+#endif
+#endif /* !Py_SYSMODULE_H */