diff --git a/testing/web-platform/meta/custom-elements/reactions/HTMLModElement.html.ini b/testing/web-platform/meta/custom-elements/reactions/HTMLModElement.html.ini
new file mode 100644
index 000000000000..fd96df8084c0
--- /dev/null
+++ b/testing/web-platform/meta/custom-elements/reactions/HTMLModElement.html.ini
@@ -0,0 +1,7 @@
+[HTMLModElement.html]
+  [dateTime on del use HTMLModElement must enqueue an attributeChanged reaction when adding dateTime content attribute]
+    expected: FAIL
+
+  [dateTime on ins use HTMLModElement must enqueue an attributeChanged reaction when adding dateTime content attribute]
+    expected: FAIL
+
diff --git a/testing/web-platform/meta/custom-elements/reactions/HTMLTimeElement.html.ini b/testing/web-platform/meta/custom-elements/reactions/HTMLTimeElement.html.ini
new file mode 100644
index 000000000000..b8352c688a83
--- /dev/null
+++ b/testing/web-platform/meta/custom-elements/reactions/HTMLTimeElement.html.ini
@@ -0,0 +1,4 @@
+[HTMLTimeElement.html]
+  [dateTime on HTMLTimeElement must enqueue an attributeChanged reaction when adding dateTime content attribute]
+    expected: FAIL
+