diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c
index c11427a1f66..01f6d2001e1 100644
--- a/src/backend/executor/execGrouping.c
+++ b/src/backend/executor/execGrouping.c
@@ -225,9 +225,8 @@ BuildTupleHashTableExt(PlanState *parent,
 	allow_jit = metacxt != tablecxt;
 
 	/* build comparator for all columns */
-	/* XXX: should we support non-minimal tuples for the inputslot? */
 	hashtable->tab_eq_func = ExecBuildGroupingEqual(inputDesc, inputDesc,
-													&TTSOpsMinimalTuple, &TTSOpsMinimalTuple,
+													NULL, &TTSOpsMinimalTuple,
 													numCols,
 													keyColIdx, eqfuncoids, collations,
 													allow_jit ? parent : NULL);
diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index a9e136ca900..e772f1d3858 100644
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -636,6 +636,21 @@ SELECT t1.id, t2.path, t2 FROM t AS t1 JOIN t AS t2 ON
  16 | {3,7,11,16} | (16,"{3,7,11,16}")
 (16 rows)
 
+CREATE TEMP TABLE duplicates (a INT NOT NULL);
+INSERT INTO duplicates VALUES(1), (1);
+-- Try out a recursive UNION case where the non-recursive part's table slot
+-- uses TTSOpsBufferHeapTuple and contains duplicate rows.
+WITH RECURSIVE cte (a) as (
+	SELECT a FROM duplicates
+	UNION
+	SELECT a FROM cte
+)
+SELECT a FROM cte;
+ a 
+---
+ 1
+(1 row)
+
 -- SEARCH clause
 create table graph0( f int, t int, label text );
 insert into graph0 values
diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index 1c8545b5b0d..5252f872ec4 100644
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -347,6 +347,18 @@ UNION ALL
 SELECT t1.id, t2.path, t2 FROM t AS t1 JOIN t AS t2 ON
 (t1.id=t2.id);
 
+CREATE TEMP TABLE duplicates (a INT NOT NULL);
+INSERT INTO duplicates VALUES(1), (1);
+
+-- Try out a recursive UNION case where the non-recursive part's table slot
+-- uses TTSOpsBufferHeapTuple and contains duplicate rows.
+WITH RECURSIVE cte (a) as (
+	SELECT a FROM duplicates
+	UNION
+	SELECT a FROM cte
+)
+SELECT a FROM cte;
+
 -- SEARCH clause
 
 create table graph0( f int, t int, label text );