diff --git a/lib/diff.c b/lib/diff.c
index bb056da4f8..38847ada6c 100644
--- a/lib/diff.c
+++ b/lib/diff.c
@@ -3720,7 +3720,7 @@ static unsigned char *deflate_it(char *data,
 				 unsigned long size,
 				 unsigned long *result_size)
 {
-	int bound;
+	size_t bound;
 	unsigned char *deflated;
 	git_zstream stream;
 	struct repo_config_values *cfg = repo_config_values(the_repository);