diff --git a/Include/modsupport.h b/Include/modsupport.h
index 6545329..5c00241 100644
--- a/Include/modsupport.h
+++ b/Include/modsupport.h
@@ -111,6 +111,8 @@
 	Py_InitModule4(name, methods, (char *)NULL, (PyObject *)NULL, \
 		       PYTHON_API_VERSION)
 
+extern char *_Py_PackageContext;
+
 #ifdef __cplusplus
 }
 #endif