diff --git a/testing/web-platform/tests/css/support/interpolation-testcommon.js b/testing/web-platform/tests/css/support/interpolation-testcommon.js
index 24c47e136c8d..9e63b02cb703 100644
--- a/testing/web-platform/tests/css/support/interpolation-testcommon.js
+++ b/testing/web-platform/tests/css/support/interpolation-testcommon.js
@@ -284,7 +284,7 @@
           comparisonFunction(
               getComputedStyle(target).getPropertyValue(property),
               expectedValue);
-        }, `${testText} at (${expectation.at}) should be [${sanitizeUrls(expectedValue)}]`);
+        }, `${testText} at (${expectation.at}) should be [${sanitizeUrls(expectation.expect)}]`);
       };
       return target;
     });