diff --git a/lib/6to5/transformation/transform.js b/lib/6to5/transformation/transform.js
index 8cb1e02098..e9153224e8 100644
--- a/lib/6to5/transformation/transform.js
+++ b/lib/6to5/transformation/transform.js
@@ -52,6 +52,7 @@ _.each({
   "spec.noForInOfAssignment":           require("./transformers/spec/no-for-in-of-assignment"),
   "spec.setters":                       require("./transformers/spec/setters"),
   "spec.blockScopedFunctions":          require("./transformers/spec/block-scoped-functions"),
+  "spec.illegalTopLevelThis":           require("./transformers/spec/illegal-top-level-this"),
 
   "playground.malletOperator":          require("./transformers/playground/mallet-operator"),
   "playground.methodBinding":           require("./transformers/playground/method-binding"),
diff --git a/lib/6to5/transformation/transformers/spec/illegal-top-level-this.js b/lib/6to5/transformation/transformers/spec/illegal-top-level-this.js
new file mode 100644
index 0000000000..e1edc90c31
--- /dev/null
+++ b/lib/6to5/transformation/transformers/spec/illegal-top-level-this.js
@@ -0,0 +1,8 @@
+exports.FunctionDeclaration =
+exports.FunctionExpression = function (node, parent, scope, context) {
+  context.skip();
+};
+
+exports.ThisExpression = function (node, parent, scope, context, file) {
+  throw file.errorWithNode(node, "Top level `this` is not allowed", ReferenceError);
+};
diff --git a/test/fixtures/transformation/es6-arrow-functions/this/actual.js b/test/fixtures/transformation/es6-arrow-functions/this/actual.js
index 8e2573dd1f..3175c884d0 100644
--- a/test/fixtures/transformation/es6-arrow-functions/this/actual.js
+++ b/test/fixtures/transformation/es6-arrow-functions/this/actual.js
@@ -1 +1,3 @@
-var t = x => this.x + x;
+function b() {
+  var t = x => this.x + x;
+}
diff --git a/test/fixtures/transformation/es6-arrow-functions/this/expected.js b/test/fixtures/transformation/es6-arrow-functions/this/expected.js
index 5206629491..358e3710a3 100644
--- a/test/fixtures/transformation/es6-arrow-functions/this/expected.js
+++ b/test/fixtures/transformation/es6-arrow-functions/this/expected.js
@@ -1,6 +1,8 @@
 "use strict";
 
-var _this = this;
-var t = function (x) {
-  return _this.x + x;
-};
+function b() {
+  var _this = this;
+  var t = function (x) {
+    return _this.x + x;
+  };
+}
diff --git a/test/fixtures/transformation/es6-destructuring/for-of/actual.js b/test/fixtures/transformation/es6-destructuring/for-of/actual.js
index 5873553d65..d8aae78557 100644
--- a/test/fixtures/transformation/es6-destructuring/for-of/actual.js
+++ b/test/fixtures/transformation/es6-destructuring/for-of/actual.js
@@ -1,3 +1,3 @@
-for (var [ name, before, after ] of this.test.expectation.registers) {
+for (var [ name, before, after ] of test.expectation.registers) {
 
 }
diff --git a/test/fixtures/transformation/es6-destructuring/for-of/expected.js b/test/fixtures/transformation/es6-destructuring/for-of/expected.js
index f29c5c92ea..d564f1bf2b 100644
--- a/test/fixtures/transformation/es6-destructuring/for-of/expected.js
+++ b/test/fixtures/transformation/es6-destructuring/for-of/expected.js
@@ -16,7 +16,7 @@ var _slicedToArray = function (arr, i) {
   }
 };
 
-for (var _iterator = this.test.expectation.registers[Symbol.iterator](), _step; !(_step = _iterator.next()).done;) {
+for (var _iterator = test.expectation.registers[Symbol.iterator](), _step; !(_step = _iterator.next()).done;) {
   var _step$value = _slicedToArray(_step.value, 3);
 
   var name = _step$value[0];
diff --git a/test/fixtures/transformation/es6-destructuring/member-expression/actual.js b/test/fixtures/transformation/es6-destructuring/member-expression/actual.js
index bd5e42d7d1..8d8bc57855 100644
--- a/test/fixtures/transformation/es6-destructuring/member-expression/actual.js
+++ b/test/fixtures/transformation/es6-destructuring/member-expression/actual.js
@@ -1 +1 @@
-[this.foo, this.bar] = [1, 2];
+[foo.foo, foo.bar] = [1, 2];
diff --git a/test/fixtures/transformation/es6-destructuring/member-expression/expected.js b/test/fixtures/transformation/es6-destructuring/member-expression/expected.js
index fbaaa04184..30b475cb11 100644
--- a/test/fixtures/transformation/es6-destructuring/member-expression/expected.js
+++ b/test/fixtures/transformation/es6-destructuring/member-expression/expected.js
@@ -20,5 +20,5 @@ var _ref = [1, 2];
 
 var _ref2 = _slicedToArray(_ref, 2);
 
-this.foo = _ref2[0];
-this.bar = _ref2[1];
+foo.foo = _ref2[0];
+foo.bar = _ref2[1];
diff --git a/test/fixtures/transformation/es6-properties.computed-loose/this/actual.js b/test/fixtures/transformation/es6-properties.computed-loose/this/actual.js
index 3e3a34ef12..ebaed8a961 100644
--- a/test/fixtures/transformation/es6-properties.computed-loose/this/actual.js
+++ b/test/fixtures/transformation/es6-properties.computed-loose/this/actual.js
@@ -1,3 +1,3 @@
 var obj = {
-  ["x" + this.foo]: "heh"
+  ["x" + foo.bar]: "heh"
 };
diff --git a/test/fixtures/transformation/es6-properties.computed-loose/this/expected.js b/test/fixtures/transformation/es6-properties.computed-loose/this/expected.js
index 23b5ee17e4..c89572a402 100644
--- a/test/fixtures/transformation/es6-properties.computed-loose/this/expected.js
+++ b/test/fixtures/transformation/es6-properties.computed-loose/this/expected.js
@@ -1,9 +1,8 @@
 "use strict";
 
-var _this = this;
 var obj = (function () {
   var _obj = {};
 
-  _obj["x" + _this.foo] = "heh";
+  _obj["x" + foo.foo] = "heh";
   return _obj;
-})();
\ No newline at end of file
+})();
diff --git a/test/fixtures/transformation/es6-properties.computed/this/actual.js b/test/fixtures/transformation/es6-properties.computed/this/actual.js
index 3e3a34ef12..ebaed8a961 100644
--- a/test/fixtures/transformation/es6-properties.computed/this/actual.js
+++ b/test/fixtures/transformation/es6-properties.computed/this/actual.js
@@ -1,3 +1,3 @@
 var obj = {
-  ["x" + this.foo]: "heh"
+  ["x" + foo.bar]: "heh"
 };
diff --git a/test/fixtures/transformation/es6-properties.computed/this/expected.js b/test/fixtures/transformation/es6-properties.computed/this/expected.js
index 3c3334e470..7f573491fd 100644
--- a/test/fixtures/transformation/es6-properties.computed/this/expected.js
+++ b/test/fixtures/transformation/es6-properties.computed/this/expected.js
@@ -9,4 +9,4 @@ var _defineProperty = function (obj, key, value) {
   });
 };
 
-var obj = _defineProperty({}, "x" + this.foo, "heh");
+var obj = _defineProperty({}, "x" + foo.bar, "heh");
diff --git a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/actual.js b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/actual.js
index 88ca6d7a77..2c800f1558 100644
--- a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/actual.js
+++ b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/actual.js
@@ -1,3 +1,3 @@
 <Component
-  {...this.props}
+  {...props}
   sound="moo" />
diff --git a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
index 9ef7b00ddf..3912b9765a 100644
--- a/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
+++ b/test/fixtures/transformation/react/adds-appropriate-newlines-when-using-spread-attribute/expected.js
@@ -1,2 +1,2 @@
-React.createElement(Component, React.__spread({}, this.props, {
+React.createElement(Component, React.__spread({}, props, {
   sound: "moo" }));
diff --git a/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/actual.js b/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/actual.js
index 37ab4f48f1..0304845f88 100644
--- a/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/actual.js
+++ b/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/actual.js
@@ -3,11 +3,11 @@ var x = <div>
 </div>;
 
 var x = <div>
-  {this.props.children}
+  {props.children}
 </div>;
 
 var x = <Composite>
-  {this.props.children}
+  {props.children}
 </Composite>;
 
 var x = <Composite>
diff --git a/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/expected.js b/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/expected.js
index 300998b04d..d233c84a8c 100644
--- a/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/expected.js
+++ b/test/fixtures/transformation/react/should-avoid-wrapping-in-extra-parens-if-not-needed/expected.js
@@ -7,13 +7,13 @@ var x = React.createElement(
 var x = React.createElement(
   "div",
   null,
-  this.props.children
+  props.children
 );
 
 var x = React.createElement(
   Composite,
   null,
-  this.props.children
+  props.children
 );
 
 var x = React.createElement(
diff --git a/test/fixtures/transformation/spec-illegal-top-level-this/arrow-function/actual.js b/test/fixtures/transformation/spec-illegal-top-level-this/arrow-function/actual.js
new file mode 100644
index 0000000000..608cf2d314
--- /dev/null
+++ b/test/fixtures/transformation/spec-illegal-top-level-this/arrow-function/actual.js
@@ -0,0 +1 @@
+var foo = () => this;
diff --git a/test/fixtures/transformation/spec-illegal-top-level-this/options.json b/test/fixtures/transformation/spec-illegal-top-level-this/options.json
new file mode 100644
index 0000000000..c1e1e00456
--- /dev/null
+++ b/test/fixtures/transformation/spec-illegal-top-level-this/options.json
@@ -0,0 +1,3 @@
+{
+  "throws": "Top level `this` is not allowed"
+}
diff --git a/test/fixtures/transformation/spec-illegal-top-level-this/root-call/actual.js b/test/fixtures/transformation/spec-illegal-top-level-this/root-call/actual.js
new file mode 100644
index 0000000000..6fcdaabcee
--- /dev/null
+++ b/test/fixtures/transformation/spec-illegal-top-level-this/root-call/actual.js
@@ -0,0 +1 @@
+this.foo();
diff --git a/test/fixtures/transformation/spec-illegal-top-level-this/root-declaration/actual.js b/test/fixtures/transformation/spec-illegal-top-level-this/root-declaration/actual.js
new file mode 100644
index 0000000000..466a452f66
--- /dev/null
+++ b/test/fixtures/transformation/spec-illegal-top-level-this/root-declaration/actual.js
@@ -0,0 +1 @@
+var self = this;
diff --git a/test/fixtures/transformation/spec-illegal-top-level-this/root-reference/actual.js b/test/fixtures/transformation/spec-illegal-top-level-this/root-reference/actual.js
new file mode 100644
index 0000000000..b251f26b7a
--- /dev/null
+++ b/test/fixtures/transformation/spec-illegal-top-level-this/root-reference/actual.js
@@ -0,0 +1 @@
+this;