diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index a2f67f2..c45a488 100644
*** a/src/backend/access/common/heaptuple.c
--- b/src/backend/access/common/heaptuple.c
*************** slot_attisnull(TupleTableSlot *slot, int
*** 1367,1372 ****
--- 1367,1398 ----
  }
  
  /*
+  * slot_getsysattr
+  *		This function fetches a system attribute of the slot's current tuple.
+  *		Unlike slot_getattr, if the slot does not contain system attributes,
+  *		this will return false (with a NULL attribute value) instead of
+  *		throwing an error.
+  */
+ bool
+ slot_getsysattr(TupleTableSlot *slot, int attnum,
+ 				Datum *value, bool *isnull)
+ {
+ 	HeapTuple	tuple = slot->tts_tuple;
+ 
+ 	Assert(attnum < 0);			/* else caller error */
+ 	if (tuple == NULL ||
+ 		tuple == &(slot->tts_minhdr))
+ 	{
+ 		/* No physical tuple, or minimal tuple, so fail */
+ 		*value = (Datum) 0;
+ 		*isnull = true;
+ 		return false;
+ 	}
+ 	*value = heap_getsysattr(tuple, attnum, slot->tts_tupleDescriptor, isnull);
+ 	return true;
+ }
+ 
+ /*
   * heap_freetuple
   */
  void
diff --git a/src/backend/executor/execCurrent.c b/src/backend/executor/execCurrent.c
index ce7d4ac..2296c9b 100644
*** a/src/backend/executor/execCurrent.c
--- b/src/backend/executor/execCurrent.c
*************** execCurrentOf(CurrentOfExpr *cexpr,
*** 150,157 ****
  	else
  	{
  		ScanState  *scanstate;
  		bool		lisnull;
- 		Oid			tuple_tableoid PG_USED_FOR_ASSERTS_ONLY;
  		ItemPointer tuple_tid;
  
  		/*
--- 150,157 ----
  	else
  	{
  		ScanState  *scanstate;
+ 		Datum		ldatum;
  		bool		lisnull;
  		ItemPointer tuple_tid;
  
  		/*
*************** execCurrentOf(CurrentOfExpr *cexpr,
*** 183,201 ****
  		if (TupIsNull(scanstate->ss_ScanTupleSlot))
  			return false;
  
! 		/* Use slot_getattr to catch any possible mistakes */
! 		tuple_tableoid =
! 			DatumGetObjectId(slot_getattr(scanstate->ss_ScanTupleSlot,
! 										  TableOidAttributeNumber,
! 										  &lisnull));
! 		Assert(!lisnull);
! 		tuple_tid = (ItemPointer)
! 			DatumGetPointer(slot_getattr(scanstate->ss_ScanTupleSlot,
! 										 SelfItemPointerAttributeNumber,
! 										 &lisnull));
  		Assert(!lisnull);
  
! 		Assert(tuple_tableoid == table_oid);
  
  		*current_tid = *tuple_tid;
  
--- 183,213 ----
  		if (TupIsNull(scanstate->ss_ScanTupleSlot))
  			return false;
  
! 		/*
! 		 * Try to fetch tableoid and CTID from the scan node's current tuple.
! 		 * If the scan type hasn't provided a physical tuple, we have to fail.
! 		 */
! 		if (!slot_getsysattr(scanstate->ss_ScanTupleSlot,
! 							 TableOidAttributeNumber,
! 							 &ldatum,
! 							 &lisnull))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_INVALID_CURSOR_STATE),
! 					 errmsg("cursor \"%s\" is not a simply updatable scan of table \"%s\"",
! 							cursor_name, table_name)));
  		Assert(!lisnull);
+ 		Assert(DatumGetObjectId(ldatum) == table_oid);
  
! 		if (!slot_getsysattr(scanstate->ss_ScanTupleSlot,
! 							 SelfItemPointerAttributeNumber,
! 							 &ldatum,
! 							 &lisnull))
! 			ereport(ERROR,
! 					(errcode(ERRCODE_INVALID_CURSOR_STATE),
! 					 errmsg("cursor \"%s\" is not a simply updatable scan of table \"%s\"",
! 							cursor_name, table_name)));
! 		Assert(!lisnull);
! 		tuple_tid = (ItemPointer) DatumGetPointer(ldatum);
  
  		*current_tid = *tuple_tid;
  
diff --git a/src/include/executor/tuptable.h b/src/include/executor/tuptable.h
index 0642a3a..a5779b1 100644
*** a/src/include/executor/tuptable.h
--- b/src/include/executor/tuptable.h
*************** extern Datum slot_getattr(TupleTableSlot
*** 170,174 ****
--- 170,176 ----
  extern void slot_getallattrs(TupleTableSlot *slot);
  extern void slot_getsomeattrs(TupleTableSlot *slot, int attnum);
  extern bool slot_attisnull(TupleTableSlot *slot, int attnum);
+ extern bool slot_getsysattr(TupleTableSlot *slot, int attnum,
+ 				Datum *value, bool *isnull);
  
  #endif							/* TUPTABLE_H */