diff --git a/trusted-types/block-string-assignment-to-Element-setAttribute.html b/trusted-types/block-string-assignment-to-Element-setAttribute.html
index 295890f319a482..e2421e4c8d18a9 100644
--- a/trusted-types/block-string-assignment-to-Element-setAttribute.html
+++ b/trusted-types/block-string-assignment-to-Element-setAttribute.html
@@ -8,6 +8,7 @@
   <meta http-equiv="Content-Security-Policy" content="require-trusted-types-for 'script';">
 </head>
 <body>
+<iframe id="sourceFrame" src="support/document-without-trusted-types-and-srcdoc-attribute.html"></iframe>
 <script>
   const nullPolicy = trustedTypes.createPolicy('NullPolicy', {createScript: s => s});
 
@@ -125,4 +126,22 @@
 
     assert_equals(script.getAttribute('src'), RESULTS.SCRIPTURL);
   }, "`script.src = setAttributeNode(embed.src)` with string works.");
+
+  async_test(t => {
+    const sourceFrame = document.getElementById("sourceFrame");
+    const targetFrame = document.createElement("iframe");
+    document.body.append(targetFrame);
+
+    t.add_cleanup(() => {
+      targetFrame.remove();
+      sourceFrame.contentWindow.location.reload();
+    });
+
+    sourceFrame.addEventListener("load", t.step_func_done(() => {
+      const div = sourceFrame.contentDocument.body.firstChild;
+      const attrNode = div.getAttributeNode("srcdoc");
+      div.removeAttributeNode(attrNode);
+      assert_throws_js(TypeError, () => { targetFrame.setAttributeNode(attrNode); });
+    }, { once: true }));
+  }, "Importing a `srcdoc` attribute node created in a non-TT enforcing realm to an iframe throws.")
 </script>
diff --git a/trusted-types/support/document-without-trusted-types-and-srcdoc-attribute.html b/trusted-types/support/document-without-trusted-types-and-srcdoc-attribute.html
new file mode 100644
index 00000000000000..ab453d3094fd9a
--- /dev/null
+++ b/trusted-types/support/document-without-trusted-types-and-srcdoc-attribute.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<head>
+  <meta charset="utf-8">
+</head>
+<body><div srcdoc="v"></div>doc without TT</body>
