diff --git a/pack-check.c b/pack-check.c
index db3adf8781..4b089fe8ec 100644
--- a/pack-check.c
+++ b/pack-check.c
@@ -164,7 +164,7 @@ static int verify_packfile(struct repository *r,
 
 int verify_pack_index(struct packed_git *p)
 {
-	off_t index_size;
+	size_t len;
 	const unsigned char *index_base;
 	git_hash_ctx ctx;
 	unsigned char hash[GIT_MAX_RAWSZ];
@@ -172,14 +172,14 @@ int verify_pack_index(struct packed_git *p)
 
 	if (open_pack_index(p))
 		return error("packfile %s index not opened", p->pack_name);
-	index_size = p->index_size;
 	index_base = p->index_data;
+	len = p->index_size - the_hash_algo->rawsz;
 
 	/* Verify SHA1 sum of the index file */
 	the_hash_algo->init_fn(&ctx);
-	the_hash_algo->update_fn(&ctx, index_base, (unsigned int)(index_size - the_hash_algo->rawsz));
+	the_hash_algo->update_fn(&ctx, index_base, len);
 	the_hash_algo->final_fn(hash, &ctx);
-	if (!hasheq(hash, index_base + index_size - the_hash_algo->rawsz))
+	if (!hasheq(hash, index_base + len))
 		err = error("Packfile index for %s hash mismatch",
 			    p->pack_name);
 	return err;