diff --git a/sys/kern/subr_fattime.c b/sys/kern/subr_fattime.c
--- a/sys/kern/subr_fattime.c
+++ b/sys/kern/subr_fattime.c
@@ -143,6 +143,8 @@
 	unsigned t2, l, m;
 
 	t1 = tsp->tv_sec;
+	if (t1 < 0)
+		t1 = 0;
 	if (!utc)
 		t1 -= 0; // XXX utc_offset();