diff --git a/expression/constant_propagation.go b/expression/constant_propagation.go
index d44fa53328..f5e8bca8a3 100644
--- a/expression/constant_propagation.go
+++ b/expression/constant_propagation.go
@@ -20,7 +20,6 @@ import (
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/util/chunk"
-	"github.com/pingcap/tidb/util/collate"
 	"github.com/pingcap/tidb/util/disjointset"
 	"github.com/pingcap/tidb/util/logutil"
 	"go.uber.org/zap"
@@ -88,7 +87,7 @@ func validEqualCondHelper(ctx sessionctx.Context, eq *ScalarFunction, colIsLeft
 	if ContainMutableConst(ctx, []Expression{con}) {
 		return nil, nil
 	}
-	if !collate.CompatibleCollate(col.GetType().Collate, con.GetType().Collate) {
+	if col.GetType().Collate != con.GetType().Collate {
 		return nil, nil
 	}
 	return col, con
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 9018f89dbb..b31bafe2a5 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -6412,6 +6412,13 @@ func (s *testIntegrationSerialSuite) TestCollateConstantPropagation(c *C) {
 	tk.MustExec("insert into t1 values ('ß', 's');")
 	tk.MustExec("insert into t2 values ('s', 's')")
 	tk.MustQuery("select * from t1 left join t2 on t1.a = t2.a collate utf8mb4_unicode_ci where t1.a = 's';").Check(testkit.Rows("ß s <nil> <nil>"))
+	tk.MustExec("drop table if exists t1, t2;")
+	tk.MustExec("create table t1(a char(10) collate utf8mb4_general_ci, index (a));")
+	tk.MustExec("create table t2(a char(10) collate utf8_bin, index (a));")
+	tk.MustExec("insert into t1 values ('a');")
+	tk.MustExec("insert into t2 values ('A');")
+	tk.MustExec("set names utf8 collate utf8_general_ci;")
+	tk.MustQuery("select * from t1, t2 where t1.a=t2.a and t1.a= 'a';").Check(testkit.Rows("a A"))
 }
 
 func (s *testIntegrationSuite2) TestIssue17791(c *C) {