diff --git a/sdhcp.c b/sdhcp.c
index 1fcf5e6..21e6372 100644
--- a/sdhcp.c
+++ b/sdhcp.c
@@ -434,12 +434,13 @@ Bound:
 	optget(&bp, mask, OBmask, sizeof(mask));
 	optget(&bp, router, OBrouter, sizeof(router));
 	optget(&bp, dns, OBdnsserver, sizeof(dns));
-	optget(&bp, &renewaltime, ODrenewaltime, sizeof(renewaltime));
-	optget(&bp, &rebindingtime, ODrebindingtime, sizeof(rebindingtime));
 	optget(&bp, &lease, ODlease, sizeof(lease));
-	renewaltime = ntohl(renewaltime);
-	rebindingtime = ntohl(rebindingtime);
 	lease = ntohl(lease);
+	/* Renew and rebind times are optional. It is faster to just
+	 * calculate the times. Assumes: lease > 4s and < ~20 years.
+	 */
+	renewaltime   = lease / 2;
+	rebindingtime = lease * 7 / 8;
 	acceptlease();
 	fputs("Congrats! You should be on the 'net.\n", stdout);
 	if (!fflag && !forked) {