diff --git a/test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js b/test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
new file mode 100644
index 0000000000..b147acc92e
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
@@ -0,0 +1,49 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.indexof
+description: Throws a TypeError if this has a detached buffer
+info: |
+  %TypedArray%.prototype.indexOf ( searchElement [ , fromIndex ] )
+
+  The interpretation and use of the arguments of %TypedArray%.prototype.indexOf are the same as for Array.prototype.indexOf as defined in 22.1.3.14.
+
+  When the indexOf method is called with one or two arguments, the following steps are taken:
+
+  Let O be the this value.
+  Perform ? ValidateTypedArray(O).
+  Let len be O.[[ArrayLength]].
+  If len is 0, return -1F.
+  Let n be ? ToIntegerOrInfinity(fromIndex).
+  Assert: If fromIndex is undefined, then n is 0.
+  If n is +∞, return -1F.
+  Else if n is -∞, set n to 0.
+  If n ≥ 0, then
+    Let k be n.
+  Else,
+    Let k be len + n.
+  If k < 0, set k to 0.
+  Repeat, while k < len,
+    Let kPresent be ! HasProperty(O, ! ToString(F(k))).
+    If kPresent is true, then
+      Let elementK be ! Get(O, ! ToString(F(k))).
+      Let same be the result of performing Strict Equality Comparison searchElement === elementK.
+      If same is true, return F(k).
+    Set k to k + 1.
+  Return -1F.
+
+includes: [testBigIntTypedArray.js, detachArrayBuffer.js]
+features: [align-detached-buffer-semantics-with-web-reality, BigInt, TypedArray]
+---*/
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const sample = new TA(1);
+  const fromIndex = {
+    valueOf() {
+      $DETACHBUFFER(sample.buffer);
+      return 0;
+    }
+  };
+
+  assert.sameValue(sample.indexOf(undefined, fromIndex), -1);
+});
diff --git a/test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one.js b/test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
similarity index 100%
rename from test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one.js
rename to test/built-ins/TypedArray/prototype/indexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
diff --git a/test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js b/test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
new file mode 100644
index 0000000000..afc2df938d
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
@@ -0,0 +1,49 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.indexof
+description: Returns -1 if buffer is detached after ValidateTypedArray
+info: |
+  %TypedArray%.prototype.indexOf ( searchElement [ , fromIndex ] )
+
+  The interpretation and use of the arguments of %TypedArray%.prototype.indexOf are the same as for Array.prototype.indexOf as defined in 22.1.3.14.
+
+  When the indexOf method is called with one or two arguments, the following steps are taken:
+
+  Let O be the this value.
+  Perform ? ValidateTypedArray(O).
+  Let len be O.[[ArrayLength]].
+  If len is 0, return -1F.
+  Let n be ? ToIntegerOrInfinity(fromIndex).
+  Assert: If fromIndex is undefined, then n is 0.
+  If n is +∞, return -1F.
+  Else if n is -∞, set n to 0.
+  If n ≥ 0, then
+    Let k be n.
+  Else,
+    Let k be len + n.
+  If k < 0, set k to 0.
+  Repeat, while k < len,
+    Let kPresent be ! HasProperty(O, ! ToString(F(k))).
+    If kPresent is true, then
+      Let elementK be ! Get(O, ! ToString(F(k))).
+      Let same be the result of performing Strict Equality Comparison searchElement === elementK.
+      If same is true, return F(k).
+    Set k to k + 1.
+  Return -1F.
+
+includes: [testTypedArray.js, detachArrayBuffer.js]
+features: [align-detached-buffer-semantics-with-web-reality, TypedArray]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  const sample = new TA(1);
+  const fromIndex = {
+    valueOf() {
+      $DETACHBUFFER(sample.buffer);
+      return 0;
+    }
+  };
+
+  assert.sameValue(sample.indexOf(undefined, fromIndex), -1);
+});
diff --git a/test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one.js b/test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
similarity index 100%
rename from test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one.js
rename to test/built-ins/TypedArray/prototype/indexOf/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
diff --git a/test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js b/test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
new file mode 100644
index 0000000000..327965c0e6
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
@@ -0,0 +1,46 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.lastindexof
+description: Returns -1 if buffer is detached after ValidateTypedArray
+info: |
+  %TypedArray%.prototype.lastIndexOf ( searchElement [ , fromIndex ] )
+
+  The interpretation and use of the arguments of %TypedArray%.prototype.lastIndexOf are the same as for Array.prototype.lastIndexOf as defined in 22.1.3.17.
+
+  When the lastIndexOf method is called with one or two arguments, the following steps are taken:
+
+  Let O be the this value.
+  Perform ? ValidateTypedArray(O).
+  Let len be O.[[ArrayLength]].
+  If len is 0, return -1F.
+  If fromIndex is present, let n be ? ToIntegerOrInfinity(fromIndex); else let n be len - 1.
+  If n is -∞, return -1F.
+  If n ≥ 0, then
+    Let k be min(n, len - 1).
+  Else,
+    Let k be len + n.
+  Repeat, while k ≥ 0,
+    Let kPresent be ! HasProperty(O, ! ToString(F(k))).
+    If kPresent is true, then
+      Let elementK be ! Get(O, ! ToString(F(k))).
+      Let same be the result of performing Strict Equality Comparison searchElement === elementK.
+      If same is true, return F(k).
+    Set k to k - 1.
+  Return -1F.
+
+includes: [testBigIntTypedArray.js, detachArrayBuffer.js]
+features: [align-detached-buffer-semantics-with-web-reality, BigInt, TypedArray]
+---*/
+
+testWithBigIntTypedArrayConstructors(function(TA) {
+  const sample = new TA(1);
+  const fromIndex = {
+    valueOf() {
+      $DETACHBUFFER(sample.buffer);
+      return 0;
+    }
+  };
+
+  assert.sameValue(sample.lastIndexOf(undefined, fromIndex), -1);
+});
diff --git a/test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one.js b/test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
similarity index 100%
rename from test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one.js
rename to test/built-ins/TypedArray/prototype/lastIndexOf/BigInt/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
diff --git a/test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js b/test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
new file mode 100644
index 0000000000..0f8094e221
--- /dev/null
+++ b/test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one-for-undefined.js
@@ -0,0 +1,46 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-%typedarray%.prototype.lastindexof
+description: Returns -1 if buffer is detached after ValidateTypedArray
+info: |
+  %TypedArray%.prototype.lastIndexOf ( searchElement [ , fromIndex ] )
+
+  The interpretation and use of the arguments of %TypedArray%.prototype.lastIndexOf are the same as for Array.prototype.lastIndexOf as defined in 22.1.3.17.
+
+  When the lastIndexOf method is called with one or two arguments, the following steps are taken:
+
+  Let O be the this value.
+  Perform ? ValidateTypedArray(O).
+  Let len be O.[[ArrayLength]].
+  If len is 0, return -1F.
+  If fromIndex is present, let n be ? ToIntegerOrInfinity(fromIndex); else let n be len - 1.
+  If n is -∞, return -1F.
+  If n ≥ 0, then
+    Let k be min(n, len - 1).
+  Else,
+    Let k be len + n.
+  Repeat, while k ≥ 0,
+    Let kPresent be ! HasProperty(O, ! ToString(F(k))).
+    If kPresent is true, then
+      Let elementK be ! Get(O, ! ToString(F(k))).
+      Let same be the result of performing Strict Equality Comparison searchElement === elementK.
+      If same is true, return F(k).
+    Set k to k - 1.
+  Return -1F.
+
+includes: [testTypedArray.js, detachArrayBuffer.js]
+features: [align-detached-buffer-semantics-with-web-reality, TypedArray]
+---*/
+
+testWithTypedArrayConstructors(function(TA) {
+  const sample = new TA(1);
+  const fromIndex = {
+    valueOf() {
+      $DETACHBUFFER(sample.buffer);
+      return 0;
+    }
+  };
+
+  assert.sameValue(sample.lastIndexOf(undefined, fromIndex), -1);
+});
diff --git a/test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one.js b/test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js
similarity index 100%
rename from test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one.js
rename to test/built-ins/TypedArray/prototype/lastIndexOf/detached-buffer-during-fromIndex-returns-minus-one-for-zero.js