diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index f4689e7c9f8..846bd7c1fbe 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -1081,6 +1081,18 @@ subquery_planner(PlannerGlobal *glob, Query *parse, char *plan_name,
 		/* exclRelTlist contains only Vars, so no preprocessing needed */
 	}
 
+	if (parse->forPortionOf)
+	{
+		parse->forPortionOf->targetRange =
+			preprocess_expression(root,
+								  parse->forPortionOf->targetRange,
+								  EXPRKIND_TARGET);
+		if (contain_volatile_functions(parse->forPortionOf->targetRange))
+			ereport(ERROR,
+					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+					 errmsg("FOR PORTION OF bounds cannot contain volatile functions")));
+	}
+
 	foreach(l, parse->mergeActionList)
 	{
 		MergeAction *action = (MergeAction *) lfirst(l);
diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 93fa66ae57c..76758adefb6 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -1489,9 +1489,6 @@ transformForPortionOfClause(ParseState *pstate,
 													args,
 													InvalidOid, InvalidOid, COERCE_EXPLICIT_CALL);
 	}
-	if (contain_volatile_functions_after_planning((Expr *) result->targetRange))
-		ereport(ERROR,
-				(errmsg("FOR PORTION OF bounds cannot contain volatile functions")));
 
 	/*
 	 * Build overlapsExpr to use as an extra qual. This means we only hit rows