diff --git a/tests/system-test/2-query/concat.py b/tests/system-test/2-query/concat.py
index f2f231a858..2c3667959e 100644
--- a/tests/system-test/2-query/concat.py
+++ b/tests/system-test/2-query/concat.py
@@ -146,7 +146,7 @@ class TDTestCase:
         ]
         tdSql.query("select concat(null,null)")  # TD-31571
         tdSql.checkRows(1)
-        tdSql.getData(0, 0) == "NULL"
+        assert tdSql.getData(0, 0) == None
         for tb in tbname:
             for i in range(2,8):
                 self.__concat_check(tb,i)
diff --git a/tests/system-test/2-query/concat_ws.py b/tests/system-test/2-query/concat_ws.py
index e0fc260527..29df526ff8 100644
--- a/tests/system-test/2-query/concat_ws.py
+++ b/tests/system-test/2-query/concat_ws.py
@@ -158,7 +158,7 @@ class TDTestCase:
         ]
         tdSql.query("select concat_ws(null,null,null);")  # TD-31572
         tdSql.checkRows(1)
-        tdSql.getData(0, 0) == "NULL"
+        assert tdSql.getData(0, 0) == None
         for tb in tbname:
             for errsql in self.__concat_ws_err_check(tb):
                 tdSql.error(sql=errsql)