diff --git a/src/backend/executor/nodeWindowAgg.c b/src/backend/executor/nodeWindowAgg.c
index 418d6d9c426..3e7436f4918 100644
--- a/src/backend/executor/nodeWindowAgg.c
+++ b/src/backend/executor/nodeWindowAgg.c
@@ -2294,6 +2294,23 @@ ExecWindowAgg(PlanState *pstate)
 				 */
 				if (winstate->use_pass_through)
 				{
+					/*
+					 * When switching into a pass-through mode, we'd better
+					 * NULLify the aggregate results as these are no longer
+					 * updated and NULLifying them avoids the old stale
+					 * results lingering.  Some of these might be byref types
+					 * so we can't have them pointing to free'd memory.  The
+					 * planner insisted that quals used in the runcondition
+					 * are strict, so the top-level WindowAgg will always
+					 * filter these NULLs out in the filter clause.
+					 */
+					numfuncs = winstate->numfuncs;
+					for (i = 0; i < numfuncs; i++)
+					{
+						econtext->ecxt_aggvalues[i] = (Datum) 0;
+						econtext->ecxt_aggnulls[i] = true;
+					}
+
 					/*
 					 * STRICT pass-through mode is required for the top window
 					 * when there is a PARTITION BY clause.  Otherwise we must
@@ -2308,24 +2325,6 @@ ExecWindowAgg(PlanState *pstate)
 					else
 					{
 						winstate->status = WINDOWAGG_PASSTHROUGH;
-
-						/*
-						 * If we're not the top-window, we'd better NULLify
-						 * the aggregate results.  In pass-through mode we no
-						 * longer update these and this avoids the old stale
-						 * results lingering.  Some of these might be byref
-						 * types so we can't have them pointing to free'd
-						 * memory.  The planner insisted that quals used in
-						 * the runcondition are strict, so the top-level
-						 * WindowAgg will filter these NULLs out in the filter
-						 * clause.
-						 */
-						numfuncs = winstate->numfuncs;
-						for (i = 0; i < numfuncs; i++)
-						{
-							econtext->ecxt_aggvalues[i] = (Datum) 0;
-							econtext->ecxt_aggnulls[i] = true;
-						}
 					}
 				}
 				else
diff --git a/src/test/regress/expected/window.out b/src/test/regress/expected/window.out
index f8914c0401c..d626591a05d 100644
--- a/src/test/regress/expected/window.out
+++ b/src/test/regress/expected/window.out
@@ -3663,6 +3663,16 @@ WHERE c = 1;
    ->  Seq Scan on empsalary
 (3 rows)
 
+-- Try another case with a WindowFunc with a byref return type
+SELECT * FROM
+  (SELECT row_number() OVER (PARTITION BY salary) AS rn,
+          lead(depname) OVER (PARTITION BY salary) || ' Department' AS n_dep
+   FROM empsalary) emp
+WHERE rn < 1;
+ rn | n_dep 
+----+-------
+(0 rows)
+
 -- Some more complex cases with multiple window clauses
 EXPLAIN (COSTS OFF)
 SELECT * FROM
diff --git a/src/test/regress/sql/window.sql b/src/test/regress/sql/window.sql
index 2a5aa38d29a..edf17e50a47 100644
--- a/src/test/regress/sql/window.sql
+++ b/src/test/regress/sql/window.sql
@@ -1161,6 +1161,13 @@ SELECT * FROM
    FROM empsalary) emp
 WHERE c = 1;
 
+-- Try another case with a WindowFunc with a byref return type
+SELECT * FROM
+  (SELECT row_number() OVER (PARTITION BY salary) AS rn,
+          lead(depname) OVER (PARTITION BY salary) || ' Department' AS n_dep
+   FROM empsalary) emp
+WHERE rn < 1;
+
 -- Some more complex cases with multiple window clauses
 EXPLAIN (COSTS OFF)
 SELECT * FROM