diff --git a/Python/pyhash.c b/Python/pyhash.c
index 4c0b929..d381dc0 100644
--- a/Python/pyhash.c
+++ b/Python/pyhash.c
@@ -129,7 +129,7 @@
 }
 
 Py_hash_t
-_Py_HashPointer(void *p)
+_Py_HashPointer(const void *p)
 {
     Py_hash_t x;
     size_t y = (size_t)p;