diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 040eb50078c..954266bc1c5 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -18779,6 +18779,7 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 	HeapTuple	tuple,
 				newtuple;
 	Relation	trigrel = NULL;
+	List	   *fkoids = NIL;
 
 	if (concurrent)
 	{
@@ -18799,6 +18800,27 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 	fks = copyObject(RelationGetFKeyList(partRel));
 	if (fks != NIL)
 		trigrel = table_open(TriggerRelationId, RowExclusiveLock);
+
+	/*
+	 * It's possible that the partition being detached has a foreign key that
+	 * references a partitioned table.  When that happens, there are multiple
+	 * pg_constraint rows for the partition: one points to the partitioned
+	 * table itself, while the others point to each of its partitions.  Only
+	 * the topmost one is to be considered here; the child constraints must be
+	 * left alone, because conceptually those aren't coming from our parent
+	 * partitioned table, but from this partition itself.
+	 *
+	 * We implement this by collecting all the constraint OIDs in a first scan
+	 * of the FK array, and skipping in the loop below those constraints whose
+	 * parents are listed here.
+	 */
+	foreach(cell, fks)
+	{
+		ForeignKeyCacheInfo *fk = (ForeignKeyCacheInfo *) lfirst(cell);
+
+		fkoids = lappend_oid(fkoids, fk->conoid);
+	}
+
 	foreach(cell, fks)
 	{
 		ForeignKeyCacheInfo *fk = lfirst(cell);
@@ -18812,9 +18834,13 @@ DetachPartitionFinalize(Relation rel, Relation partRel, bool concurrent,
 			elog(ERROR, "cache lookup failed for constraint %u", fk->conoid);
 		conform = (Form_pg_constraint) GETSTRUCT(contup);
 
-		/* consider only the inherited foreign keys */
+		/*
+		 * Consider only inherited foreign keys, and only if their parents
+		 * aren't in the list.
+		 */
 		if (conform->contype != CONSTRAINT_FOREIGN ||
-			!OidIsValid(conform->conparentid))
+			!OidIsValid(conform->conparentid) ||
+			list_member_oid(fkoids, conform->conparentid))
 		{
 			ReleaseSysCache(contup);
 			continue;
diff --git a/src/test/regress/expected/foreign_key.out b/src/test/regress/expected/foreign_key.out
index 6b8c2f24142..84745b9f60c 100644
--- a/src/test/regress/expected/foreign_key.out
+++ b/src/test/regress/expected/foreign_key.out
@@ -2339,6 +2339,13 @@ UPDATE pk SET a = 4002 WHERE a = 4000;
 DELETE FROM pk WHERE a = 4002;
 UPDATE pk SET a = 4502 WHERE a = 4500;
 DELETE FROM pk WHERE a = 4502;
+-- Also, detaching a partition that has the FK itself should work
+-- https://postgr.es/m/CAAJ_b97GuPh6wQPbxQS-Zpy16Oh+0aMv-w64QcGrLhCOZZ6p+g@mail.gmail.com
+CREATE TABLE ffk (a int, b int REFERENCES pk) PARTITION BY list (a);
+CREATE TABLE ffk1 PARTITION OF ffk FOR VALUES IN (1);
+ALTER TABLE ffk1 ADD FOREIGN KEY (a) REFERENCES pk;
+ALTER TABLE ffk DETACH PARTITION ffk1;
+DROP TABLE ffk, ffk1;
 CREATE SCHEMA fkpart4;
 SET search_path TO fkpart4;
 -- dropping/detaching PARTITIONs is prevented if that would break
diff --git a/src/test/regress/sql/foreign_key.sql b/src/test/regress/sql/foreign_key.sql
index 45c7a534cb1..9f4210b26e5 100644
--- a/src/test/regress/sql/foreign_key.sql
+++ b/src/test/regress/sql/foreign_key.sql
@@ -1672,6 +1672,14 @@ DELETE FROM pk WHERE a = 4002;
 UPDATE pk SET a = 4502 WHERE a = 4500;
 DELETE FROM pk WHERE a = 4502;
 
+-- Also, detaching a partition that has the FK itself should work
+-- https://postgr.es/m/CAAJ_b97GuPh6wQPbxQS-Zpy16Oh+0aMv-w64QcGrLhCOZZ6p+g@mail.gmail.com
+CREATE TABLE ffk (a int, b int REFERENCES pk) PARTITION BY list (a);
+CREATE TABLE ffk1 PARTITION OF ffk FOR VALUES IN (1);
+ALTER TABLE ffk1 ADD FOREIGN KEY (a) REFERENCES pk;
+ALTER TABLE ffk DETACH PARTITION ffk1;
+DROP TABLE ffk, ffk1;
+
 CREATE SCHEMA fkpart4;
 SET search_path TO fkpart4;
 -- dropping/detaching PARTITIONs is prevented if that would break