diff --git a/layout/style/GeckoBindings.cpp b/layout/style/GeckoBindings.cpp
index b48fe0adb2d4..9ec29b9a2299 100644
--- a/layout/style/GeckoBindings.cpp
+++ b/layout/style/GeckoBindings.cpp
@@ -1192,7 +1192,12 @@ void Gecko_GetComputedImageURLSpec(const StyleComputedUrl* aURL,
     }
   }
 
-  aOut->AssignLiteral("about:invalid");
+  // Empty URL computes to empty, per spec:
+  if (aURL->SpecifiedSerialization().IsEmpty()) {
+    aOut->Truncate();
+  } else {
+    aOut->AssignLiteral("about:invalid");
+  }
 }
 
 bool Gecko_IsSupportedImageMimeType(const uint8_t* aMimeType,
diff --git a/testing/web-platform/meta/css/css-values/urls/empty.html.ini b/testing/web-platform/meta/css/css-values/urls/empty.html.ini
deleted file mode 100644
index ebdc17c25b8e..000000000000
--- a/testing/web-platform/meta/css/css-values/urls/empty.html.ini
+++ /dev/null
@@ -1,20 +0,0 @@
-[empty.html]
-  [empty URL: inline-unquoted]
-    expected:
-      if (os == "mac") and not debug: [FAIL, PASS]
-      FAIL
-
-  [empty URL: inline-quoted]
-    expected:
-      if (os == "mac") and not debug: [FAIL, PASS]
-      FAIL
-
-  [empty URL: external-unquoted]
-    expected:
-      if (os == "mac") and not debug: [FAIL, PASS]
-      FAIL
-
-  [empty URL: external-quoted]
-    expected:
-      if (os == "mac") and not debug: [FAIL, PASS]
-      FAIL