diff --git a/Tests/LibWeb/TestConfig.ini b/Tests/LibWeb/TestConfig.ini
index c986374bc58..e3ec7071372 100644
--- a/Tests/LibWeb/TestConfig.ini
+++ b/Tests/LibWeb/TestConfig.ini
@@ -44,9 +44,13 @@ Text/input/wpt-import/html/syntax/parsing/html5lib_tests19.html
 Text/input/wpt-import/html/syntax/parsing/html5lib_tests5.html
 Text/input/wpt-import/html/syntax/parsing/html5lib_webkit01.html
 Text/input/wpt-import/html/syntax/parsing/named-character-references.html
+
+; Support files (not tests themselves)
 Text/input/wpt-import/html/syntax/parsing/support/no-doctype-name-eof.html
 Text/input/wpt-import/html/syntax/parsing/support/no-doctype-name-line.html
 Text/input/wpt-import/html/syntax/parsing/support/no-doctype-name-space.html
+Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/sandbox_allow_script.html
+Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/blank.htm
 
 ; Unknown, imported as skipped in #2148
 Text/input/wpt-import/html/infrastructure/safe-passing-of-structured-data/structuredclone_0.html
diff --git a/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.txt b/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.txt
new file mode 100644
index 00000000000..3b538906604
--- /dev/null
+++ b/Tests/LibWeb/Text/expected/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.txt
@@ -0,0 +1,7 @@
+Harness status: OK
+
+Found 2 tests
+
+2 Fail
+Fail	iframe 'sandbox' ASCII case insensitive, allow-same-orİgin
+Fail	iframe 'sandbox' ASCII case insensitive, allow-ſcripts
\ No newline at end of file
diff --git a/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.html b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.html
new file mode 100644
index 00000000000..1769ddd9a5e
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/sandbox-ascii-case-insensitive.html
@@ -0,0 +1,41 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>iframe 'sandbox' ASCII case insensitive</title>
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#attr-iframe-sandbox">
+<script src="../../../../resources/testharness.js"></script>
+<script src="../../../../resources/testharnessreport.js"></script>
+<body>
+<script>
+async_test(function(t) {
+  let iframe = document.createElement('iframe');
+  iframe.setAttribute('sandbox', 'allow-same-or\u0130gin');
+  iframe.setAttribute('hidden', '');
+
+  assert_true(iframe.sandbox.supports('allow-same-origin'), 'supports the allow-same-origin token');
+
+  iframe.src = 'support/blank.htm';
+  iframe.onload = t.step_func_done(function() {
+    try {
+      assert_equals(iframe.contentDocument, null, 'child document not reachable');
+    } catch (e) {
+      // The assert_equals throwing is a pass.
+    }
+  });
+  document.body.appendChild(iframe);
+}, document.title + ', allow-same-or\u0130gin');
+
+async_test(function(t) {
+  let iframe = document.createElement('iframe');
+  iframe.setAttribute('sandbox', 'allow-\u017Fcripts');
+  iframe.setAttribute('hidden', '');
+
+  assert_true(iframe.sandbox.supports('allow-scripts'), 'supports the allow-scripts token');
+
+  window.onmessage = t.unreached_func('no scripts should run in the iframe');
+  iframe.src = 'support/sandbox_allow_script.html';
+  iframe.onload = t.step_func(function() {
+    t.step_timeout(t.step_func_done(), 100);
+  });
+  document.body.appendChild(iframe);
+}, document.title + ', allow-\u017Fcripts');
+</script>
diff --git a/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/blank.htm b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/blank.htm
new file mode 100644
index 00000000000..18ecdcb795c
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/blank.htm
@@ -0,0 +1 @@
+<html></html>
diff --git a/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/sandbox_allow_script.html b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/sandbox_allow_script.html
new file mode 100644
index 00000000000..a2d5b73eda8
--- /dev/null
+++ b/Tests/LibWeb/Text/input/wpt-import/html/semantics/embedded-content/the-iframe-element/support/sandbox_allow_script.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<meta charset="utf-8">
+<title>HTML Test: sandbox_allow_scripts</title>
+<link rel="author" title="Intel" href="http://www.intel.com/">
+<div id="test">Before change</div>
+<script>
+  parent.window.postMessage("Script executed", "*");
+</script>
