diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 6543eedc3a..1dae356360 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -14726,7 +14726,7 @@ ATExecDetachPartition(Relation rel, RangeVar *name)
 	if (OidIsValid(defaultPartOid))
 		LockRelationOid(defaultPartOid, AccessExclusiveLock);
 
-	partRel = heap_openrv(name, AccessShareLock);
+	partRel = heap_openrv(name, ShareUpdateExclusiveLock);
 
 	/* All inheritance related checks are performed within the function */
 	RemoveInheritance(partRel, rel);