diff --git a/usr.sbin/sendmail/src/util.c b/usr.sbin/sendmail/src/util.c
index 3065e382b248..b492a2e5bf82 100644
--- a/usr.sbin/sendmail/src/util.c
+++ b/usr.sbin/sendmail/src/util.c
@@ -418,7 +418,7 @@ buildfname(gecos, login, buf, buflen)
 	{
 		if (*p == '&')
 		{
-			snprintf(bp, SPACELEFT(buf, bp), "%s", login);
+			snprintf(bp, buflen - (bp - buf), "%s", login);
 			*bp = toupper(*bp);
 			bp += strlen(bp);
 		}