diff --git a/src/backend/catalog/catalog.c b/src/backend/catalog/catalog.c
index 11ee536..92d943c 100644
*** a/src/backend/catalog/catalog.c
--- b/src/backend/catalog/catalog.c
***************
*** 38,43 ****
--- 38,44 ----
  #include "catalog/pg_shseclabel.h"
  #include "catalog/pg_subscription.h"
  #include "catalog/pg_tablespace.h"
+ #include "catalog/pg_type.h"
  #include "catalog/toasting.h"
  #include "miscadmin.h"
  #include "storage/fd.h"
*************** GetNewOidWithIndex(Relation relation, Oi
*** 340,345 ****
--- 341,354 ----
  	ScanKeyData key;
  	bool		collides;
  
+ 	/*
+ 	 * We should never be asked to generate a new pg_type OID during
+ 	 * pg_upgrade; doing so would risk collisions with the OIDs it wants to
+ 	 * assign.  Hitting this assert means there's some path where we failed to
+ 	 * ensure that a type OID is determined by commands in the dump script.
+ 	 */
+ 	Assert(!IsBinaryUpgrade || RelationGetRelid(relation) != TypeRelationId);
+ 
  	InitDirtySnapshot(SnapshotDirty);
  
  	/* Generate new OIDs until we find one not in the table */
*************** GetNewRelFileNode(Oid reltablespace, Rel
*** 391,396 ****
--- 400,412 ----
  	bool		collides;
  	BackendId	backend;
  
+ 	/*
+ 	 * If we ever get here during pg_upgrade, there's something wrong; all
+ 	 * relfilenode assignments during a binary-upgrade run should be
+ 	 * determined by commands in the dump script.
+ 	 */
+ 	Assert(!IsBinaryUpgrade);
+ 
  	switch (relpersistence)
  	{
  		case RELPERSISTENCE_TEMP: