diff --git a/src/option.c b/src/option.c
index 98bac5a..df81cf3 100644
--- a/src/option.c
+++ b/src/option.c
@@ -1932,7 +1932,7 @@
 	int	    cp_val,
 	char_u	    *varp_arg,
 	char	    *errbuf,
-	int	    errbuflen,
+	size_t	    errbuflen,
 	int	    *value_checked,
 	char	    **errmsg)
 {