diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 0c3e2b0..976de99 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -56,6 +56,7 @@
 #include "access/xlogutils.h"
 #include "catalog/catalog.h"
 #include "catalog/namespace.h"
+#include "executor/tuptable.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
@@ -4337,7 +4338,7 @@ l2:
  */
 static bool
 heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum,
-					   HeapTuple tup1, HeapTuple tup2)
+					   TupleTableSlot *tup1, TupleTableSlot *tup2)
 {
 	Datum		value1,
 				value2;
@@ -4366,13 +4367,10 @@ heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum,
 	}
 
 	/*
-	 * Extract the corresponding values.  XXX this is pretty inefficient if
-	 * there are many indexed columns.  Should HeapDetermineModifiedColumns do
-	 * a single heap_deform_tuple call on each tuple, instead?	But that
-	 * doesn't work for system columns ...
+	 * Extract the corresponding values.
 	 */
-	value1 = heap_getattr(tup1, attrnum, tupdesc, &isnull1);
-	value2 = heap_getattr(tup2, attrnum, tupdesc, &isnull2);
+	value1 = slot_getattr(tup1, attrnum, &isnull1);
+	value2 = slot_getattr(tup2, attrnum, &isnull2);
 
 	/*
 	 * If one value is NULL and other is not, then they are certainly not
@@ -4424,17 +4422,27 @@ HeapDetermineModifiedColumns(Relation relation, Bitmapset *interesting_cols,
 {
 	int		attnum;
 	Bitmapset *modified = NULL;
+	TupleTableSlot *oldslot;
+	TupleTableSlot *newslot;
+
+	oldslot = MakeSingleTupleTableSlot(RelationGetDescr(relation));
+	ExecStoreTuple(oldtup, oldslot, InvalidBuffer, false);
+	newslot = MakeSingleTupleTableSlot(RelationGetDescr(relation));
+	ExecStoreTuple(newtup, newslot, InvalidBuffer, false);
 
 	while ((attnum = bms_first_member(interesting_cols)) >= 0)
 	{
 		attnum += FirstLowInvalidHeapAttributeNumber;
 
 		if (!heap_tuple_attr_equals(RelationGetDescr(relation),
-								   attnum, oldtup, newtup))
+									attnum, oldslot, newslot))
 			modified = bms_add_member(modified,
 									  attnum - FirstLowInvalidHeapAttributeNumber);
 	}
 
+	ExecDropSingleTupleTableSlot(oldslot);
+	ExecDropSingleTupleTableSlot(newslot);
+
 	return modified;
 }