diff --git a/src/lib/commands/buy.c b/src/lib/commands/buy.c
index e7a8ef70..f3c36151 100644
--- a/src/lib/commands/buy.c
+++ b/src/lib/commands/buy.c
@@ -161,16 +161,10 @@ buy(void)
 	return RET_FAIL;
     if (bid > 0.04 + comm.com_price) {
 	comm.com_price = bid;
-	/* Add five minutes to the time if less than 5 minutes */
 	time(&now);
-	if (((MARK_DELAY - (now - comm.com_markettime)) < 300) &&
-	    comm.com_maxbidder != player->cnum) {
-	    comm.com_markettime += 300;
-	    /* Special case - what if so much time has gone by?  Well,
-	       Just reset the markettime  so that only 5 minutes are left */
-	    if ((MARK_DELAY - (now - comm.com_markettime)) < 0)
-		comm.com_markettime = (now - (MARK_DELAY - 300));
-	}
+	if (comm.com_markettime + MARK_DELAY - now < minutes(5) &&
+	    comm.com_maxbidder != player->cnum)
+	    comm.com_markettime = now + minutes(5) - MARK_DELAY;
 	comm.com_maxbidder = player->cnum;
 	comm.com_x = x;
 	comm.com_y = y;
diff --git a/src/lib/commands/trad.c b/src/lib/commands/trad.c
index fa122e8b..6a850568 100644
--- a/src/lib/commands/trad.c
+++ b/src/lib/commands/trad.c
@@ -254,11 +254,10 @@ trad(void)
 	return RET_OK;
     }
     if (bid > trade.trd_price) {
-	/* Add five minutes to the time if less than 5 minutes left. */
 	time(&now);
-	if (((TRADE_DELAY - (now - trade.trd_markettime)) < 300) &&
+	if (trade.trd_markettime  + TRADE_DELAY - now < minutes(5) &&
 	    trade.trd_maxbidder != player->cnum)
-	    trade.trd_markettime += 300;
+	    trade.trd_markettime = now + minutes(5) - TRADE_DELAY;
 	trade.trd_price = bid;
 	trade.trd_maxbidder = player->cnum;
 	trade.trd_x = sx;