diff --git a/lib/6to5/transformation/transformers/other/use-strict.js b/lib/6to5/transformation/transformers/other/use-strict.js
index 3965a463de..2d3c6750bd 100644
--- a/lib/6to5/transformation/transformers/other/use-strict.js
+++ b/lib/6to5/transformation/transformers/other/use-strict.js
@@ -17,5 +17,5 @@ exports.FunctionExpression = function (node, parent, scope, context) {
 };
 
 exports.ThisExpression = function (node, parent, scope, context, file) {
-  throw file.errorWithNode(node, "Top level `this` is `undefined` in strict mode", ReferenceError);
+  return t.identifier("undefined");
 };
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-call/options.json b/test/fixtures/transformation/use-strict/illegal-this-root-call/options.json
deleted file mode 100644
index 3137168db6..0000000000
--- a/test/fixtures/transformation/use-strict/illegal-this-root-call/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Top level `this` is `undefined` in strict mode"
-}
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-declaration/options.json b/test/fixtures/transformation/use-strict/illegal-this-root-declaration/options.json
deleted file mode 100644
index 3137168db6..0000000000
--- a/test/fixtures/transformation/use-strict/illegal-this-root-declaration/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Top level `this` is `undefined` in strict mode"
-}
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-reference/options.json b/test/fixtures/transformation/use-strict/illegal-this-root-reference/options.json
deleted file mode 100644
index 3137168db6..0000000000
--- a/test/fixtures/transformation/use-strict/illegal-this-root-reference/options.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "throws": "Top level `this` is `undefined` in strict mode"
-}
diff --git a/test/fixtures/transformation/use-strict/illegal-this-arrow-function/actual.js b/test/fixtures/transformation/use-strict/undefined-this-arrow-function/actual.js
similarity index 100%
rename from test/fixtures/transformation/use-strict/illegal-this-arrow-function/actual.js
rename to test/fixtures/transformation/use-strict/undefined-this-arrow-function/actual.js
diff --git a/test/fixtures/transformation/use-strict/undefined-this-arrow-function/expected.js b/test/fixtures/transformation/use-strict/undefined-this-arrow-function/expected.js
new file mode 100644
index 0000000000..bf107937df
--- /dev/null
+++ b/test/fixtures/transformation/use-strict/undefined-this-arrow-function/expected.js
@@ -0,0 +1,5 @@
+"use strict";
+
+var foo = function () {
+  return undefined;
+};
\ No newline at end of file
diff --git a/test/fixtures/transformation/use-strict/illegal-this-arrow-function/options.json b/test/fixtures/transformation/use-strict/undefined-this-arrow-function/options.json
similarity index 100%
rename from test/fixtures/transformation/use-strict/illegal-this-arrow-function/options.json
rename to test/fixtures/transformation/use-strict/undefined-this-arrow-function/options.json
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-call/actual.js b/test/fixtures/transformation/use-strict/undefined-this-root-call/actual.js
similarity index 100%
rename from test/fixtures/transformation/use-strict/illegal-this-root-call/actual.js
rename to test/fixtures/transformation/use-strict/undefined-this-root-call/actual.js
diff --git a/test/fixtures/transformation/use-strict/undefined-this-root-call/expected.js b/test/fixtures/transformation/use-strict/undefined-this-root-call/expected.js
new file mode 100644
index 0000000000..269a449b01
--- /dev/null
+++ b/test/fixtures/transformation/use-strict/undefined-this-root-call/expected.js
@@ -0,0 +1,3 @@
+"use strict";
+
+undefined.foo();
\ No newline at end of file
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-declaration/actual.js b/test/fixtures/transformation/use-strict/undefined-this-root-declaration/actual.js
similarity index 100%
rename from test/fixtures/transformation/use-strict/illegal-this-root-declaration/actual.js
rename to test/fixtures/transformation/use-strict/undefined-this-root-declaration/actual.js
diff --git a/test/fixtures/transformation/use-strict/undefined-this-root-declaration/expected.js b/test/fixtures/transformation/use-strict/undefined-this-root-declaration/expected.js
new file mode 100644
index 0000000000..e9be05fae1
--- /dev/null
+++ b/test/fixtures/transformation/use-strict/undefined-this-root-declaration/expected.js
@@ -0,0 +1,3 @@
+"use strict";
+
+var self = undefined;
\ No newline at end of file
diff --git a/test/fixtures/transformation/use-strict/illegal-this-root-reference/actual.js b/test/fixtures/transformation/use-strict/undefined-this-root-reference/actual.js
similarity index 100%
rename from test/fixtures/transformation/use-strict/illegal-this-root-reference/actual.js
rename to test/fixtures/transformation/use-strict/undefined-this-root-reference/actual.js
diff --git a/test/fixtures/transformation/use-strict/undefined-this-root-reference/expected.js b/test/fixtures/transformation/use-strict/undefined-this-root-reference/expected.js
new file mode 100644
index 0000000000..34c5918e4c
--- /dev/null
+++ b/test/fixtures/transformation/use-strict/undefined-this-root-reference/expected.js
@@ -0,0 +1,3 @@
+"use strict";
+
+undefined;
\ No newline at end of file