diff --git a/test/built-ins/String/prototype/trimEnd/this-value-not-obj-coercible.js b/test/built-ins/String/prototype/trimEnd/this-value-not-obj-coercible.js
new file mode 100644
index 0000000000000000000000000000000000000000..2800be27362148a3fcdc5373bb823b1d75412c97
--- /dev/null
+++ b/test/built-ins/String/prototype/trimEnd/this-value-not-obj-coercible.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2017 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: pending
+description: The "this" value must be object-coercible
+info: |
+  1. Let O be ? RequireObjectCoercible(this value).
+---*/
+
+var trimEnd = String.prototype.trimEnd;
+
+assert.sameValue(typeof trimEnd, 'function');
+
+assert.throws(TypeError, function() {
+  trimEnd.call(undefined);
+}, 'undefined');
+
+assert.throws(TypeError, function() {
+  trimEnd.call(null);
+}, 'null');
diff --git a/test/built-ins/String/prototype/trimStart/this-value-not-obj-coercible.js b/test/built-ins/String/prototype/trimStart/this-value-not-obj-coercible.js
new file mode 100644
index 0000000000000000000000000000000000000000..c7afae1e1130063db233c8677aa9a4ec39da0531
--- /dev/null
+++ b/test/built-ins/String/prototype/trimStart/this-value-not-obj-coercible.js
@@ -0,0 +1,21 @@
+// Copyright (C) 2017 Valerie Young. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: pending
+description: The "this" value must be object-coercible
+info: |
+  1. Let O be ? RequireObjectCoercible(this value).
+---*/
+
+var trimStart = String.prototype.trimStart;
+
+assert.sameValue(typeof trimStart, 'function');
+
+assert.throws(TypeError, function() {
+  trimStart.call(undefined);
+}, 'undefined');
+
+assert.throws(TypeError, function() {
+  trimStart.call(null);
+}, 'null');