diff --git a/executor/join_test.go b/executor/join_test.go
index 7277d70d07c67..798fe6554e5d9 100644
--- a/executor/join_test.go
+++ b/executor/join_test.go
@@ -1427,3 +1427,11 @@ func (s *testSuite2) TestIssue11390(c *C) {
 	tk.MustExec("insert into 11390t values(1, 1)")
 	tk.MustQuery("select /*+ TIDB_INLJ(t1, t2) */ * from 11390t t1, 11390t t2 where t1.k2 > 0 and t1.k2 = t2.k2 and t2.k1=1;").Check(testkit.Rows("1 1 1 1"))
 }
+
+func (s *testSuite2) TestIssue14514(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t")
+	tk.MustExec("create table t (pk varchar(14) primary key, a varchar(12));")
+	tk.MustQuery("select * from (select t1.pk or '/' as c from t as t1 left join t as t2 on t1.a = t2.pk) as t where t.c = 1;").Check(testkit.Rows())
+}
diff --git a/expression/expression.go b/expression/expression.go
index a1322fce450f5..e487cf3a8ca5e 100644
--- a/expression/expression.go
+++ b/expression/expression.go
@@ -398,7 +398,7 @@ func wrapWithIsTrue(ctx sessionctx.Context, keepNull bool, arg Expression) (Expr
 		return nil, err
 	}
 	sf := &ScalarFunction{
-		FuncName: model.NewCIStr(fmt.Sprintf("sig_%T", f)),
+		FuncName: model.NewCIStr(ast.IsTruth),
 		Function: f,
 		RetType:  f.getRetTp(),
 	}