diff --git a/expression/integration_test.go b/expression/integration_test.go
index 80f087d2821d1..f8ed485f7008b 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -556,7 +556,6 @@ func (s *testIntegrationSuite) TestMathBuiltin(c *C) {
 }
 
 func (s *testIntegrationSuite) TestStringBuiltin(c *C) {
-	c.Assert(s.ctx.GetSessionVars().SetSystemVar(variable.MaxAllowedPacket, "67108864"), IsNil)
 	defer s.cleanEnv(c)
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
diff --git a/planner/core/logical_plan_test.go b/planner/core/logical_plan_test.go
index 6f1ea8be27a47..536ac04908964 100644
--- a/planner/core/logical_plan_test.go
+++ b/planner/core/logical_plan_test.go
@@ -29,7 +29,6 @@ import (
 	"github.com/pingcap/tidb/infoschema"
 	"github.com/pingcap/tidb/planner/property"
 	"github.com/pingcap/tidb/sessionctx"
-	"github.com/pingcap/tidb/sessionctx/variable"
 	"github.com/pingcap/tidb/util/testleak"
 )
 
@@ -1361,7 +1360,6 @@ func (s *testPlanSuite) TestValidate(c *C) {
 			err: ErrUnknownColumn,
 		},
 	}
-	s.ctx.GetSessionVars().SetSystemVar(variable.MaxAllowedPacket, "67108864")
 	for _, tt := range tests {
 		sql := tt.sql
 		comment := Commentf("for %s", sql)