diff --git a/tests/wpt/metadata-layout-2020/css/css-ui/parsing/outline-width-computed.html.ini b/tests/wpt/metadata-layout-2020/css/css-ui/parsing/outline-width-computed.html.ini
index 53533b58872..93fdc34e6ec 100644
--- a/tests/wpt/metadata-layout-2020/css/css-ui/parsing/outline-width-computed.html.ini
+++ b/tests/wpt/metadata-layout-2020/css/css-ui/parsing/outline-width-computed.html.ini
@@ -12,3 +12,6 @@
   [Property outline-width value '0.5em']
     expected: FAIL
 
+  [Property outline-width value '2.5px']
+    expected: FAIL
+