diff --git a/sys/kern/subr_sbuf.c b/sys/kern/subr_sbuf.c
index cd3295fd0b55..68a7b156cb34 100644
--- a/sys/kern/subr_sbuf.c
+++ b/sys/kern/subr_sbuf.c
@@ -706,9 +706,10 @@ sbuf_finish(struct sbuf *s)
 #ifdef _KERNEL
 	return (s->s_error);
 #else
-	errno = s->s_error;
-	if (s->s_error)
+	if (s->s_error != 0) {
+		errno = s->s_error;
 		return (-1);
+	}
 	return (0);
 #endif
 }