diff --git a/hash.c b/hash.c
index 4615c47b82..0ac95730b3 100644
--- a/hash.c
+++ b/hash.c
@@ -271,7 +271,7 @@ key64_hash (uint64_t key, uint32_t seed)
 long
 rb_objid_hash(st_index_t index)
 {
-    return key64_hash(index, (uint32_t) prime2);
+    return (long)key64_hash(index, (uint32_t)prime2);
 }
 
 static st_index_t