diff --git a/builtin/unpack-objects.c b/builtin/unpack-objects.c
index 4a9466295ba10d..ad3b494bb2f1a6 100644
--- a/builtin/unpack-objects.c
+++ b/builtin/unpack-objects.c
@@ -320,7 +320,7 @@ static void added_object(unsigned nr, enum object_type type,
 	}
 }
 
-static void unpack_non_delta_entry(enum object_type type, unsigned long size,
+static void unpack_non_delta_entry(enum object_type type, size_t size,
 				   unsigned nr)
 {
 	void *buf = get_data(size);