diff --git a/src/compiler/transformers/es2015.ts b/src/compiler/transformers/es2015.ts
index 65771410ea2..da0fcc73a98 100644
--- a/src/compiler/transformers/es2015.ts
+++ b/src/compiler/transformers/es2015.ts
@@ -859,7 +859,7 @@ namespace ts {
                 statements.push(
                     setTextRange(
                         createStatement(
-                            createExtendsHelper(context, getLocalName(node))
+                            createExtendsHelper(context, getInternalName(node))
                         ),
                         /*location*/ extendsClauseElement
                     )
diff --git a/tests/baselines/reference/classExtensionNameOutput.js b/tests/baselines/reference/classExtensionNameOutput.js
new file mode 100644
index 00000000000..8f979863426
--- /dev/null
+++ b/tests/baselines/reference/classExtensionNameOutput.js
@@ -0,0 +1,38 @@
+//// [classExtensionNameOutput.ts]
+class A {}
+if (true) {
+  class B extends A {}
+
+  const foo = function () {
+    new B();
+  }
+}
+
+//// [classExtensionNameOutput.js]
+var __extends = (this && this.__extends) || (function () {
+    var extendStatics = Object.setPrototypeOf ||
+        ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
+        function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
+    return function (d, b) {
+        extendStatics(d, b);
+        function __() { this.constructor = d; }
+        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
+    };
+})();
+var A = /** @class */ (function () {
+    function A() {
+    }
+    return A;
+}());
+if (true) {
+    var B_1 = /** @class */ (function (_super) {
+        __extends(B, _super);
+        function B() {
+            return _super !== null && _super.apply(this, arguments) || this;
+        }
+        return B;
+    }(A));
+    var foo = function () {
+        new B_1();
+    };
+}
diff --git a/tests/baselines/reference/classExtensionNameOutput.symbols b/tests/baselines/reference/classExtensionNameOutput.symbols
new file mode 100644
index 00000000000..7c26d980295
--- /dev/null
+++ b/tests/baselines/reference/classExtensionNameOutput.symbols
@@ -0,0 +1,16 @@
+=== tests/cases/compiler/classExtensionNameOutput.ts ===
+class A {}
+>A : Symbol(A, Decl(classExtensionNameOutput.ts, 0, 0))
+
+if (true) {
+  class B extends A {}
+>B : Symbol(B, Decl(classExtensionNameOutput.ts, 1, 11))
+>A : Symbol(A, Decl(classExtensionNameOutput.ts, 0, 0))
+
+  const foo = function () {
+>foo : Symbol(foo, Decl(classExtensionNameOutput.ts, 4, 7))
+
+    new B();
+>B : Symbol(B, Decl(classExtensionNameOutput.ts, 1, 11))
+  }
+}
diff --git a/tests/baselines/reference/classExtensionNameOutput.types b/tests/baselines/reference/classExtensionNameOutput.types
new file mode 100644
index 00000000000..0bbbb9e2119
--- /dev/null
+++ b/tests/baselines/reference/classExtensionNameOutput.types
@@ -0,0 +1,20 @@
+=== tests/cases/compiler/classExtensionNameOutput.ts ===
+class A {}
+>A : A
+
+if (true) {
+>true : true
+
+  class B extends A {}
+>B : B
+>A : A
+
+  const foo = function () {
+>foo : () => void
+>function () {    new B();  } : () => void
+
+    new B();
+>new B() : B
+>B : typeof B
+  }
+}
diff --git a/tests/cases/compiler/classExtensionNameOutput.ts b/tests/cases/compiler/classExtensionNameOutput.ts
new file mode 100644
index 00000000000..3992780b0fb
--- /dev/null
+++ b/tests/cases/compiler/classExtensionNameOutput.ts
@@ -0,0 +1,8 @@
+class A {}
+if (true) {
+  class B extends A {}
+
+  const foo = function () {
+    new B();
+  }
+}
\ No newline at end of file