diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 0355b52ed4..bff05267fb 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -1725,35 +1725,35 @@ static Node *
 fix_alternative_subplan(PlannerInfo *root, AlternativeSubPlan *asplan,
 						double num_exec)
 {
-	SubPlan    *subplan1;
-	SubPlan    *subplan2;
-	Cost		cost1;
-	Cost		cost2;
+	SubPlan    *bestplan = NULL;
+	Cost		bestcost;
 	ListCell   *lc;
 
-	/* Currently there will always be exactly 2 alternatives */
-	Assert(list_length(asplan->subplans) == 2);
-	subplan1 = (SubPlan *) linitial(asplan->subplans);
-	subplan2 = (SubPlan *) lsecond(asplan->subplans);
+	Assert(list_length(asplan->subplans) > 0);
 
-	/* Choose the one that's cheaper assuming num_exec executions */
-	cost1 = subplan1->startup_cost + num_exec * subplan1->per_call_cost;
-	cost2 = subplan2->startup_cost + num_exec * subplan2->per_call_cost;
-
-	if (cost1 < cost2)
-	{
-		/* Delete subplan2 and return subplan1 */
-		lc = list_nth_cell(root->glob->subplans, subplan2->plan_id - 1);
-		lfirst(lc) = NULL;
-		return (Node *) subplan1;
-	}
-	else
+	foreach(lc, asplan->subplans)
 	{
-		/* Delete subplan1 and return subplan2 */
-		lc = list_nth_cell(root->glob->subplans, subplan1->plan_id - 1);
-		lfirst(lc) = NULL;
-		return (Node *) subplan2;
+		SubPlan    *curplan = (SubPlan *) lfirst(lc);
+		Cost		curcost;
+
+		curcost = curplan->startup_cost + num_exec * curplan->per_call_cost;
+		if (bestplan == NULL)
+		{
+			bestplan = curplan;
+			bestcost = curcost;
+		}
+		else if (curcost < bestcost)
+		{
+			/* NULLify discarded subplan */
+			lc = list_nth_cell(root->glob->subplans, bestplan->plan_id - 1);
+			lfirst(lc) = NULL;
+
+			bestplan = curplan;
+			bestcost = curcost;
+		}
 	}
+
+	return (Node *) bestplan;
 }
 
 /*
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index fd65ee8f9c..21ccb4f026 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -739,10 +739,7 @@ typedef struct SubPlan
  * This is used only transiently during planning: by the time the plan
  * reaches the executor, all AlternativeSubPlan nodes have been removed.
  *
- * The subplans are given as a List so that the node definition need not
- * change if there's ever more than two alternatives.  For the moment,
- * though, there are always exactly two; and the first one is the fast-start
- * plan.
+ * The subplans List must contain at least one subplan.
  */
 typedef struct AlternativeSubPlan
 {