diff --git a/Include/pythread.h b/Include/pythread.h
index f26db16..b5a6ec3 100644
--- a/Include/pythread.h
+++ b/Include/pythread.h
@@ -40,6 +40,9 @@
 PyAPI_FUNC(void *) PyThread_get_key_value(int);
 PyAPI_FUNC(void) PyThread_delete_key_value(int key);
 
+/* Cleanup after a fork */
+PyAPI_FUNC(void) PyThread_ReInitTLS(void);
+
 #ifdef __cplusplus
 }
 #endif