diff --git a/core/planner.c b/core/planner.c
index a4c93ba77..d7aaf97b7 100644
--- a/core/planner.c
+++ b/core/planner.c
@@ -1087,7 +1087,7 @@ bool plan(struct deco_state *ds, struct diveplan *diveplan, struct dive *dive, i
 		 * otherwise odd things can happen, such as CVA causing the final ascent to start *later*
 		 * if the ascent rate is slower, which is completely nonsensical.
 		 * Assume final ascent takes 20s, which is the time taken to ascend at 9m/min from 3m */
-		ds->deco_time = clock - bottom_time - stoplevels[stopidx + 1] / last_ascend_rate + 20;
+		ds->deco_time = clock - bottom_time - (M_OR_FT(3,10) * ( prefs.last_stop ? 2 : 1)) / last_ascend_rate + 20;
 	} while (!is_final_plan);
 	decostoptable[decostopcounter].depth = 0;