diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index 71ed6a4880..cebfe19734 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -314,9 +314,10 @@ create_plan(PlannerInfo *root, Path *best_path)
 
 	/*
 	 * Attach any initPlans created in this query level to the topmost plan
-	 * node.  (The initPlans could actually go in any plan node at or above
-	 * where they're referenced, but there seems no reason to put them any
-	 * lower than the topmost node for the query level.)
+	 * node.  (In principle the initplans could go in any plan node at or
+	 * above where they're referenced, but there seems no reason to put them
+	 * any lower than the topmost node for the query level.  Also, see
+	 * comments for SS_finalize_plan before you try to change this.)
 	 */
 	SS_attach_initplans(root, plan);
 
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index 0ece4f2aac..a66317367c 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -305,15 +305,33 @@ standard_planner(Query *parse, int cursorOptions, ParamListInfo boundParams)
 	if (cursorOptions & CURSOR_OPT_SCROLL)
 	{
 		if (!ExecSupportsBackwardScan(top_plan))
-			top_plan = materialize_finished_plan(top_plan);
+		{
+			Plan	   *sub_plan = top_plan;
+
+			top_plan = materialize_finished_plan(sub_plan);
+
+			/*
+			 * XXX horrid kluge: if there are any initPlans attached to the
+			 * formerly-top plan node, move them up to the Material node. This
+			 * prevents failure in SS_finalize_plan, which see for comments.
+			 * We don't bother adjusting the sub_plan's cost estimate for
+			 * this.
+			 */
+			top_plan->initPlan = sub_plan->initPlan;
+			sub_plan->initPlan = NIL;
+		}
 	}
 
 	/*
 	 * Optionally add a Gather node for testing purposes, provided this is
-	 * actually a safe thing to do.
+	 * actually a safe thing to do.  (Note: we assume adding a Material node
+	 * above did not change the parallel safety of the plan, so we can still
+	 * rely on best_path->parallel_safe.  However, that flag doesn't account
+	 * for initPlans, which render the plan parallel-unsafe.)
 	 */
-	if (best_path->parallel_safe &&
-		force_parallel_mode != FORCE_PARALLEL_OFF)
+	if (force_parallel_mode != FORCE_PARALLEL_OFF &&
+		best_path->parallel_safe &&
+		top_plan->initPlan == NIL)
 	{
 		Gather	   *gather = makeNode(Gather);
 
diff --git a/src/backend/optimizer/plan/subselect.c b/src/backend/optimizer/plan/subselect.c
index 0849b1d563..a46cc10820 100644
--- a/src/backend/optimizer/plan/subselect.c
+++ b/src/backend/optimizer/plan/subselect.c
@@ -2187,7 +2187,7 @@ SS_charge_for_initplans(PlannerInfo *root, RelOptInfo *final_rel)
  *
  * Attach any initplans created in the current query level to the specified
  * plan node, which should normally be the topmost node for the query level.
- * (The initPlans could actually go in any node at or above where they're
+ * (In principle the initPlans could go in any node at or above where they're
  * referenced; but there seems no reason to put them any lower than the
  * topmost node, so we don't bother to track exactly where they came from.)
  * We do not touch the plan node's cost; the initplans should have been
@@ -2226,9 +2226,22 @@ SS_finalize_plan(PlannerInfo *root, Plan *plan)
  * recursion.
  *
  * The return value is the computed allParam set for the given Plan node.
- * This is just an internal notational convenience.
+ * This is just an internal notational convenience: we can add a child
+ * plan's allParams to the set of param IDs of interest to this level
+ * in the same statement that recurses to that child.
  *
  * Do not scribble on caller's values of valid_params or scan_params!
+ *
+ * Note: although we attempt to deal with initPlans anywhere in the tree, the
+ * logic is not really right.  The problem is that a plan node might return an
+ * output Param of its initPlan as a targetlist item, in which case it's valid
+ * for the parent plan level to reference that same Param; the parent's usage
+ * will be converted into a Var referencing the child plan node by setrefs.c.
+ * But this function would see the parent's reference as out of scope and
+ * complain about it.  For now, this does not matter because the planner only
+ * attaches initPlans to the topmost plan node in a query level, so the case
+ * doesn't arise.  If we ever merge this processing into setrefs.c, maybe it
+ * can be handled more cleanly.
  */
 static Bitmapset *
 finalize_plan(PlannerInfo *root, Plan *plan, Bitmapset *valid_params,
diff --git a/src/test/regress/expected/portals.out b/src/test/regress/expected/portals.out
index 462ad231c3..3ae918a63c 100644
--- a/src/test/regress/expected/portals.out
+++ b/src/test/regress/expected/portals.out
@@ -1285,3 +1285,68 @@ fetch all from c;
 (3 rows)
 
 rollback;
+-- Check handling of non-backwards-scan-capable plans with scroll cursors
+begin;
+explain (costs off) declare c1 cursor for select (select 42) as x;
+        QUERY PLAN         
+---------------------------
+ Result
+   InitPlan 1 (returns $0)
+     ->  Result
+(3 rows)
+
+explain (costs off) declare c1 scroll cursor for select (select 42) as x;
+        QUERY PLAN         
+---------------------------
+ Materialize
+   InitPlan 1 (returns $0)
+     ->  Result
+   ->  Result
+(4 rows)
+
+declare c1 scroll cursor for select (select 42) as x;
+fetch all in c1;
+ x  
+----
+ 42
+(1 row)
+
+fetch backward all in c1;
+ x  
+----
+ 42
+(1 row)
+
+rollback;
+begin;
+explain (costs off) declare c2 cursor for select generate_series(1,3) as g;
+ QUERY PLAN 
+------------
+ Result
+(1 row)
+
+explain (costs off) declare c2 scroll cursor for select generate_series(1,3) as g;
+  QUERY PLAN  
+--------------
+ Materialize
+   ->  Result
+(2 rows)
+
+declare c2 scroll cursor for select generate_series(1,3) as g;
+fetch all in c2;
+ g 
+---
+ 1
+ 2
+ 3
+(3 rows)
+
+fetch backward all in c2;
+ g 
+---
+ 3
+ 2
+ 1
+(3 rows)
+
+rollback;
diff --git a/src/test/regress/sql/portals.sql b/src/test/regress/sql/portals.sql
index 01c3b85da9..a1c812e937 100644
--- a/src/test/regress/sql/portals.sql
+++ b/src/test/regress/sql/portals.sql
@@ -484,3 +484,19 @@ fetch all from c;
 move backward all in c;
 fetch all from c;
 rollback;
+
+-- Check handling of non-backwards-scan-capable plans with scroll cursors
+begin;
+explain (costs off) declare c1 cursor for select (select 42) as x;
+explain (costs off) declare c1 scroll cursor for select (select 42) as x;
+declare c1 scroll cursor for select (select 42) as x;
+fetch all in c1;
+fetch backward all in c1;
+rollback;
+begin;
+explain (costs off) declare c2 cursor for select generate_series(1,3) as g;
+explain (costs off) declare c2 scroll cursor for select generate_series(1,3) as g;
+declare c2 scroll cursor for select generate_series(1,3) as g;
+fetch all in c2;
+fetch backward all in c2;
+rollback;