diff --git a/src/core.h b/src/core.h
index d39eda4..c1ce388 100644
--- a/src/core.h
+++ b/src/core.h
@@ -40,7 +40,7 @@ struct tip_client {
 	/* for file serving. */
 	const char		*uri;
 	const char		*path;
-	size_t			size;
+	off_t			size;
 	int			fd;
 	off_t			offset;