diff --git a/src/backend/optimizer/util/appendinfo.c b/src/backend/optimizer/util/appendinfo.c
index 38f51b6607..5c3d5a736b 100644
--- a/src/backend/optimizer/util/appendinfo.c
+++ b/src/backend/optimizer/util/appendinfo.c
@@ -21,6 +21,7 @@
 #include "nodes/nodeFuncs.h"
 #include "optimizer/appendinfo.h"
 #include "optimizer/pathnode.h"
+#include "optimizer/planmain.h"
 #include "parser/parsetree.h"
 #include "utils/lsyscache.h"
 #include "utils/rel.h"
@@ -968,9 +969,10 @@ distribute_row_identity_vars(PlannerInfo *root)
 	 * certainly process no rows.  Handle this edge case by re-opening the top
 	 * result relation and adding the row identity columns it would have used,
 	 * as preprocess_targetlist() would have done if it weren't marked "inh".
-	 * (This is a bit ugly, but it seems better to confine the ugliness and
-	 * extra cycles to this unusual corner case.)  We needn't worry about
-	 * fixing the rel's reltarget, as that won't affect the finished plan.
+	 * Then re-run build_base_rel_tlists() to ensure that the added columns
+	 * get propagated to the relation's reltarget.  (This is a bit ugly, but
+	 * it seems better to confine the ugliness and extra cycles to this
+	 * unusual corner case.)
 	 */
 	if (root->row_identity_vars == NIL)
 	{
@@ -980,6 +982,8 @@ distribute_row_identity_vars(PlannerInfo *root)
 		add_row_identity_columns(root, result_relation,
 								 target_rte, target_relation);
 		table_close(target_relation, NoLock);
+		build_base_rel_tlists(root, root->processed_tlist);
+		/* There are no ROWID_VAR Vars in this case, so we're done. */
 		return;
 	}
 
diff --git a/src/test/regress/expected/merge.out b/src/test/regress/expected/merge.out
index 81c6d97d75..4da7b7845a 100644
--- a/src/test/regress/expected/merge.out
+++ b/src/test/regress/expected/merge.out
@@ -1846,6 +1846,31 @@ TABLE pa_target;
    2
 (2 rows)
 
+-- Partition-less partitioned table
+-- (the bug we are checking for appeared only if table had partitions before)
+DROP TABLE pa_targetp;
+EXPLAIN (VERBOSE, COSTS OFF)
+MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
+  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
+                 QUERY PLAN                 
+--------------------------------------------
+ Merge on public.pa_target t
+   ->  Hash Left Join
+         Output: s.sid, t.ctid
+         Hash Cond: (s.sid = t.tid)
+         ->  Seq Scan on public.pa_source s
+               Output: s.sid
+         ->  Hash
+               Output: t.tid, t.ctid
+               ->  Result
+                     Output: t.tid, t.ctid
+                     One-Time Filter: false
+(11 rows)
+
+MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
+  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
+ERROR:  no partition of relation "pa_target" found for row
+DETAIL:  Partition key of the failing row contains (tid) = (1).
 DROP TABLE pa_source;
 DROP TABLE pa_target CASCADE;
 -- some complex joins on the source side
diff --git a/src/test/regress/sql/merge.sql b/src/test/regress/sql/merge.sql
index 29a35486d0..4cf6db908b 100644
--- a/src/test/regress/sql/merge.sql
+++ b/src/test/regress/sql/merge.sql
@@ -1169,6 +1169,18 @@ MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
 
 TABLE pa_target;
 
+-- Partition-less partitioned table
+-- (the bug we are checking for appeared only if table had partitions before)
+
+DROP TABLE pa_targetp;
+
+EXPLAIN (VERBOSE, COSTS OFF)
+MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
+  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
+
+MERGE INTO pa_target t USING pa_source s ON t.tid = s.sid
+  WHEN NOT MATCHED THEN INSERT VALUES (s.sid);
+
 DROP TABLE pa_source;
 DROP TABLE pa_target CASCADE;