diff --git a/src/babel/generation/generators/modules.js b/src/babel/generation/generators/modules.js
index 2e22a5be87..33a086dc3a 100644
--- a/src/babel/generation/generators/modules.js
+++ b/src/babel/generation/generators/modules.js
@@ -79,9 +79,7 @@ export function ImportDeclaration(node, print) {
         this.push(", ");
       }
 
-      var isDefault = t.isSpecifierDefault(spec);
-
-      if (!isDefault && spec.type !== "ImportNamespaceSpecifier" && !foundImportSpecifier) {
+      if (!t.isSpecifierDefault(spec) && !foundImportSpecifier) {
         foundImportSpecifier = true;
         this.push("{ ");
       }
diff --git a/src/babel/transformation/modules/_default.js b/src/babel/transformation/modules/_default.js
index 1177bc5b01..7d2555275d 100644
--- a/src/babel/transformation/modules/_default.js
+++ b/src/babel/transformation/modules/_default.js
@@ -215,17 +215,15 @@ export default class DefaultFormatter {
   }
 
   exportAllDeclaration(node, nodes) {
-    var nodes = [];
     var ref = this.getExternalReference(node, nodes);
     nodes.push(this.buildExportsWildcard(ref, node));
-    return nodes;
   }
 
   exportSpecifier(specifier, node, nodes) {
     if (node.source) {
       var ref = this.getExternalReference(node, nodes);
 
-      if (t.isSpecifierDefault(specifier) && !this.noInteropRequireExport) {
+      if (specifier.local.name === "default" && !this.noInteropRequireExport) {
         // importing a default so we need to normalize it
         ref = t.callExpression(this.file.addHelper("interop-require"), [ref]);
       } else {
diff --git a/src/babel/transformation/transformers/es6/modules.js b/src/babel/transformation/transformers/es6/modules.js
index 28b6848275..fea77b4f9d 100644
--- a/src/babel/transformation/transformers/es6/modules.js
+++ b/src/babel/transformation/transformers/es6/modules.js
@@ -2,6 +2,14 @@ import * as t from "../../../types";
 
 export { check } from "../internal/modules";
 
+function keepBlockHoist(node, nodes) {
+  if (node._blockHoist) {
+    for (let i = 0; i < nodes.length; i++) {
+      nodes[i]._blockHoist = node._blockHoist;
+    }
+  }
+}
+
 export function ImportDeclaration(node, parent, scope, file) {
   // flow type
   if (node.isType) return;
@@ -27,12 +35,14 @@ export function ImportDeclaration(node, parent, scope, file) {
 export function ExportAllDeclaration(node, parent, scope, file) {
   var nodes = [];
   file.moduleFormatter.exportAllDeclaration(node, nodes, parent);
+  keepBlockHoist(node, nodes);
   return nodes;
 }
 
 export function ExportDefaultDeclaration(node, parent, scope, file) {
   var nodes = [];
   file.moduleFormatter.exportDeclaration(node, nodes, parent);
+  keepBlockHoist(node, nodes);
   return nodes;
 }
 
@@ -57,11 +67,7 @@ export function ExportNamedDeclaration(node, parent, scope, file) {
     }
   }
 
-  if (node._blockHoist) {
-    for (let i = 0; i < nodes.length; i++) {
-      nodes[i]._blockHoist = node._blockHoist;
-    }
-  }
+  keepBlockHoist(node, nodes);
 
   return nodes;
 }
diff --git a/src/babel/transformation/transformers/es7/object-rest-spread.js b/src/babel/transformation/transformers/es7/object-rest-spread.js
index eea9f9fa1c..771b9808b2 100644
--- a/src/babel/transformation/transformers/es7/object-rest-spread.js
+++ b/src/babel/transformation/transformers/es7/object-rest-spread.js
@@ -9,7 +9,7 @@ export var metadata = {
 };
 
 export function manipulateOptions(opts) {
-  if (opts.whitelist.length) opts.whitelist.push("es6.destructuring");
+  if (opts.whitelist) opts.whitelist.push("es6.destructuring");
 }
 
 var hasSpread = function (node) {
diff --git a/src/babel/transformation/transformers/internal/validation.js b/src/babel/transformation/transformers/internal/validation.js
index 600c2aa3d5..87119f6380 100644
--- a/src/babel/transformation/transformers/internal/validation.js
+++ b/src/babel/transformation/transformers/internal/validation.js
@@ -11,6 +11,22 @@ export function ForOfStatement(node, parent, scope, file) {
 
 export { ForOfStatement as ForInStatement };
 
+export function MethodDefinition(node) {
+  if (node.kind !== "constructor") {
+    // get constructor() {}
+    var isConstructor = !node.computed && t.isIdentifier(node.key, { name: "constructor" });
+
+    // get ["constructor"]() {}
+    isConstructor ||= t.isLiteral(node.key, { value: "constructor" });
+
+    if (isConstructor) {
+      throw this.errorWithNode(messages.get("classesIllegalConstructorKind"));
+    }
+  }
+
+  Property.apply(this, arguments);
+}
+
 export function Property(node, parent, scope, file) {
   if (node.kind === "set") {
     if (node.value.params.length !== 1) {
@@ -24,8 +40,6 @@ export function Property(node, parent, scope, file) {
   }
 }
 
-export { Property as MethodDefinition };
-
 export function BlockStatement(node) {
   for (var i = 0; i < node.body.length; i++) {
     var bodyNode = node.body[i];
diff --git a/test/fixtures/transformation/es6-arrow-functions/arguments/expected.js b/test/fixtures/transformation/es6-arrow-functions/arguments/expected.js
index 86b1ab853b..eac62b4a0e 100644
--- a/test/fixtures/transformation/es6-arrow-functions/arguments/expected.js
+++ b/test/fixtures/transformation/es6-arrow-functions/arguments/expected.js
@@ -50,7 +50,7 @@ function four() {
 four({ foo: "foo" });
 
 function five(obj) {
-  var fn = function () {
+  var fn = function fn() {
     return obj.arguments[0].foo + "bar";
   };
   return fn();
@@ -58,7 +58,7 @@ function five(obj) {
 five({ arguments: ["foo"] });
 
 function six(obj) {
-  var fn = function () {
+  var fn = function fn() {
     var fn2 = function fn2() {
       return arguments[0];
     };
diff --git a/test/fixtures/transformation/es6-block-scoping-exec/duplicate-in-upper-scope.js b/test/fixtures/transformation/es6-block-scoping-exec/duplicate-in-upper-scope.js
deleted file mode 100644
index b0c9c0f6c1..0000000000
--- a/test/fixtures/transformation/es6-block-scoping-exec/duplicate-in-upper-scope.js
+++ /dev/null
@@ -1,5 +0,0 @@
-let x = [0];
-for (let x of x) {
-  assert.equal(x, 0);
-}
-assert.deepEqual(x, [0]);
diff --git a/test/fixtures/transformation/es6-destructuring/empty-object-pattern/expected.js b/test/fixtures/transformation/es6-destructuring/empty-object-pattern/expected.js
index 93c853b604..e0b04dfea8 100644
--- a/test/fixtures/transformation/es6-destructuring/empty-object-pattern/expected.js
+++ b/test/fixtures/transformation/es6-destructuring/empty-object-pattern/expected.js
@@ -1,7 +1,4 @@
 "use strict";
 
-var _objectDestructuringEmpty = function (obj) { if (obj == null) throw new TypeError("Cannot destructure undefined"); };
-
 var _ref = null;
-
-_objectDestructuringEmpty(_ref);
+babelHelpers.objectDestructuringEmpty(_ref);
diff --git a/test/fixtures/transformation/es6-destructuring/es7-object-rest/expected.js b/test/fixtures/transformation/es6-destructuring/es7-object-rest/expected.js
index e4e278732b..cefe9cbafb 100644
--- a/test/fixtures/transformation/es6-destructuring/es7-object-rest/expected.js
+++ b/test/fixtures/transformation/es6-destructuring/es7-object-rest/expected.js
@@ -1,15 +1,10 @@
 "use strict";
 
-var _objectWithoutProperties = function (obj, keys) { var target = {}; for (var i in obj) { if (keys.indexOf(i) >= 0) continue; if (!Object.prototype.hasOwnProperty.call(obj, i)) continue; target[i] = obj[i]; } return target; };
-
-var x = _objectWithoutProperties(z, []);
-
+var x = babelHelpers.objectWithoutProperties(z, []);
 var x = z.x;
-
-var y = _objectWithoutProperties(z, ["x"]);
+var y = babelHelpers.objectWithoutProperties(z, ["x"]);
 
 (function (_ref) {
   var x = _ref.x;
-
-  var y = _objectWithoutProperties(_ref, ["x"]);
+  var y = babelHelpers.objectWithoutProperties(_ref, ["x"]);
 });