diff --git a/src/backend/catalog/pg_constraint.c b/src/backend/catalog/pg_constraint.c
index e953000c01d..043bf7c24dd 100644
--- a/src/backend/catalog/pg_constraint.c
+++ b/src/backend/catalog/pg_constraint.c
@@ -704,11 +704,7 @@ extractNotNullColumn(HeapTuple constrTup)
 		ARR_DIMS(arr)[0] != 1)
 		elog(ERROR, "conkey is not a 1-D smallint array");
 
-	memcpy(&colnum, ARR_DATA_PTR(arr), sizeof(AttrNumber));
-	Assert(colnum > 0 && colnum <= MaxAttrNumber);
-
-	if ((Pointer) arr != DatumGetPointer(adatum))
-		pfree(arr);				/* free de-toasted copy, if any */
+	colnum = ((AttrNumber *) ARR_DATA_PTR(arr))[0];
 
 	return colnum;
 }