diff --git a/test/built-ins/String/prototype/trimEnd/this-value-number.js b/test/built-ins/String/prototype/trimEnd/this-value-number.js
new file mode 100644
index 0000000000..3b7d177337
--- /dev/null
+++ b/test/built-ins/String/prototype/trimEnd/this-value-number.js
@@ -0,0 +1,48 @@
+// Copyright (c) 2017 Valerie Young.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-string.prototype.trimEnd
+description: Behavoir when "this" value is a number.
+info: |
+  TrimString
+  2. Let S be ? ToString(str).
+
+  ToString
+  Argument Type: Number
+  Result: NumberToString(argument)
+features: [string-trimming]
+---*/
+
+var trimEnd = String.prototype.trimEnd
+
+assert.sameValue(
+  trimEnd.call(NaN),
+  'NaN',
+  'String.prototype.trimEnd.call(NaN)'
+);
+
+assert.sameValue(
+  trimEnd.call(Infinity),
+  'Infinity',
+  'String.prototype.trimEnd.call(Infinity)'
+);
+
+assert.sameValue(
+  trimEnd.call(-0),
+  '0',
+  'String.prototype.trimEnd.call(-0)'
+);
+
+assert.sameValue(
+  trimEnd.call(1),
+  '1',
+  'String.prototype.trimEnd.call(1)'
+);
+
+assert.sameValue(
+  trimEnd.call(-1),
+  '-1',
+  'String.prototype.trimEnd.call(-1)'
+);
+
diff --git a/test/built-ins/String/prototype/trimStart/this-value-number.js b/test/built-ins/String/prototype/trimStart/this-value-number.js
new file mode 100644
index 0000000000..0a0420f389
--- /dev/null
+++ b/test/built-ins/String/prototype/trimStart/this-value-number.js
@@ -0,0 +1,48 @@
+// Copyright (c) 2017 Valerie Young.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-string.prototype.trimStart
+description: Behavoir when "this" value is a number.
+info: |
+  TrimString
+  2. Let S be ? ToString(str).
+
+  ToString
+  Argument Type: Number
+  Result: NumberToString(argument)
+features: [string-trimming]
+---*/
+
+var trimStart = String.prototype.trimStart
+
+assert.sameValue(
+  trimStart.call(NaN),
+  'NaN',
+  'String.prototype.trimStart.call(NaN)'
+);
+
+assert.sameValue(
+  trimStart.call(Infinity),
+  'Infinity',
+  'String.prototype.trimStart.call(Infinity)'
+);
+
+assert.sameValue(
+  trimStart.call(-0),
+  '0',
+  'String.prototype.trimStart.call(-0)'
+);
+
+assert.sameValue(
+  trimStart.call(1),
+  '1',
+  'String.prototype.trimStart.call(1)'
+);
+
+assert.sameValue(
+  trimStart.call(-1),
+  '-1',
+  'String.prototype.trimStart.call(-1)'
+);
+