diff --git a/packages/babel-helpers/src/helpers.js b/packages/babel-helpers/src/helpers.js
index 87c1cbea20..8ff523b252 100644
--- a/packages/babel-helpers/src/helpers.js
+++ b/packages/babel-helpers/src/helpers.js
@@ -362,7 +362,7 @@ helpers.get = template(`
 helpers.inherits = template(`
   (function (subClass, superClass) {
     if (typeof superClass !== "function" && superClass !== null) {
-      throw new TypeError("Super expression must either be null or a function, not " + typeof superClass);
+      throw new TypeError("Super expression must either be null or a function");
     }
     subClass.prototype = Object.create(superClass && superClass.prototype, {
       constructor: {
diff --git a/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/options.json b/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/options.json
index e5e9ad8a9a..23d21f802d 100644
--- a/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/options.json
+++ b/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/options.json
@@ -1,3 +1,3 @@
 {
-  "plugins": ["transform-es2015-classes", "transform-es2015-block-scoping"]
+  "plugins": ["transform-es2015-classes", "transform-es2015-block-scoping", "transform-es2015-typeof-symbol"]
 }
diff --git a/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/return-symbol.js b/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/return-symbol.js
new file mode 100644
index 0000000000..425fec9fea
--- /dev/null
+++ b/packages/babel-plugin-transform-es2015-classes/test/fixtures/exec/return-symbol.js
@@ -0,0 +1,9 @@
+class Foo {
+  constructor() {
+    return Symbol();
+  }
+}
+
+const f = new Foo;
+assert.ok(f instanceof Foo);
+assert.ok(typeof f === "object");
diff --git a/packages/babel-plugin-transform-es2015-classes/test/fixtures/regression/T7537/expected.js b/packages/babel-plugin-transform-es2015-classes/test/fixtures/regression/T7537/expected.js
index 57019fadbb..915863627d 100644
--- a/packages/babel-plugin-transform-es2015-classes/test/fixtures/regression/T7537/expected.js
+++ b/packages/babel-plugin-transform-es2015-classes/test/fixtures/regression/T7537/expected.js
@@ -1,8 +1,10 @@
 "use strict";
 
-function _possibleConstructorReturn(self, call) { if (call && (typeof call === "object" || typeof call === "function")) { return call; } if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
+var _typeof = typeof Symbol === "function" && typeof Symbol.iterator === "symbol" ? function (obj) { return typeof obj; } : function (obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; };
 
-function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function, not " + typeof superClass); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
+function _possibleConstructorReturn(self, call) { if (call && (_typeof(call) === "object" || typeof call === "function")) { return call; } if (!self) { throw new ReferenceError("this hasn't been initialised - super() hasn't been called"); } return self; }
+
+function _inherits(subClass, superClass) { if (typeof superClass !== "function" && superClass !== null) { throw new TypeError("Super expression must either be null or a function"); } subClass.prototype = Object.create(superClass && superClass.prototype, { constructor: { value: subClass, enumerable: false, writable: true, configurable: true } }); if (superClass) Object.setPrototypeOf ? Object.setPrototypeOf(subClass, superClass) : subClass.__proto__ = superClass; }
 
 function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }
 
diff --git a/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js b/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
index 145cf41ff6..2a10a7de5b 100644
--- a/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
+++ b/packages/babel-plugin-transform-es2015-typeof-symbol/src/index.js
@@ -1,6 +1,4 @@
 export default function({ types: t }) {
-  const IGNORE = Symbol();
-
   return {
     visitor: {
       Scope({ scope }) {
@@ -13,8 +11,7 @@ export default function({ types: t }) {
 
       UnaryExpression(path) {
         const { node, parent } = path;
-        if (node[IGNORE]) return;
-        if (path.find(path => path.node && !!path.node._generated)) return;
+        if (node.operator !== "typeof") return;
 
         if (
           path.parentPath.isBinaryExpression() &&
@@ -32,24 +29,29 @@ export default function({ types: t }) {
           }
         }
 
-        if (node.operator === "typeof") {
-          const call = t.callExpression(this.addHelper("typeof"), [
-            node.argument,
-          ]);
-          if (path.get("argument").isIdentifier()) {
-            const undefLiteral = t.stringLiteral("undefined");
-            const unary = t.unaryExpression("typeof", node.argument);
-            unary[IGNORE] = true;
-            path.replaceWith(
-              t.conditionalExpression(
-                t.binaryExpression("===", unary, undefLiteral),
-                undefLiteral,
-                call,
-              ),
-            );
-          } else {
-            path.replaceWith(call);
-          }
+        const helper = this.addHelper("typeof");
+        const isUnderHelper = path.findParent(path => {
+          return path.isVariableDeclarator() && path.node.id === helper;
+        });
+
+        if (isUnderHelper) {
+          return;
+        }
+
+        const call = t.callExpression(helper, [node.argument]);
+        const arg = path.get("argument");
+        if (arg.isIdentifier() && !path.scope.hasBinding(arg.node.name)) {
+          const undefLiteral = t.stringLiteral("undefined");
+          const unary = t.unaryExpression("typeof", node.argument);
+          path.replaceWith(
+            t.conditionalExpression(
+              t.binaryExpression("===", unary, undefLiteral),
+              undefLiteral,
+              call,
+            ),
+          );
+        } else {
+          path.replaceWith(call);
         }
       },
     },
diff --git a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/actual.js b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/actual.js
index 872484bd9c..527af8d790 100644
--- a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/actual.js
+++ b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/actual.js
@@ -3,3 +3,7 @@ assert.ok(typeof s === "symbol");
 assert.equal(typeof s, "symbol");
 assert.equal(typeof typeof s.foo, "symbol");
 typeof s === "string";
+assert.isNotOk(typeof o === "symbol");
+assert.notEqual(typeof o, "symbol");
+assert.notEqual(typeof typeof o.foo, "symbol");
+typeof o === "string";
diff --git a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/exec.js b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/exec.js
index d89051afe7..72906c476c 100644
--- a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/exec.js
+++ b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/exec.js
@@ -2,3 +2,7 @@ var s = Symbol("s");
 assert.equal(typeof s, "symbol");
 assert.ok(typeof s === "symbol");
 assert.ok(typeof Symbol.prototype === 'object', "`typeof Symbol.prototype` should be 'object'");
+assert.isNotOk(typeof o === "symbol");
+assert.notEqual(typeof o, "symbol");
+assert.notEqual(typeof typeof o, "symbol");
+typeof o === "string";
diff --git a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/expected.js b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/expected.js
index 26a766f3d5..d2ef134ade 100644
--- a/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/expected.js
+++ b/packages/babel-plugin-transform-es2015-typeof-symbol/test/fixtures/symbols/typeof/expected.js
@@ -1,5 +1,9 @@
 var s = Symbol("s");
-assert.ok((typeof s === "undefined" ? "undefined" : babelHelpers.typeof(s)) === "symbol");
-assert.equal(typeof s === "undefined" ? "undefined" : babelHelpers.typeof(s), "symbol");
+assert.ok(babelHelpers.typeof(s) === "symbol");
+assert.equal(babelHelpers.typeof(s), "symbol");
 assert.equal(babelHelpers.typeof(babelHelpers.typeof(s.foo)), "symbol");
 typeof s === "string";
+assert.isNotOk((typeof o === "undefined" ? "undefined" : babelHelpers.typeof(o)) === "symbol");
+assert.notEqual(typeof o === "undefined" ? "undefined" : babelHelpers.typeof(o), "symbol");
+assert.notEqual(babelHelpers.typeof(babelHelpers.typeof(o.foo)), "symbol");
+typeof o === "string";