diff --git a/components/script/dom/headers.rs b/components/script/dom/headers.rs
index c8d0f79fc82..ff4fb39aec8 100644
--- a/components/script/dom/headers.rs
+++ b/components/script/dom/headers.rs
@@ -96,7 +96,7 @@ impl HeadersMethods for Headers {
             .get(HeaderName::from_str(&valid_name).unwrap())
         {
             combined_value = v.as_bytes().to_vec();
-            combined_value.push(b',');
+            combined_value.extend(b", ");
         }
         combined_value.extend(valid_value.iter().cloned());
         match HeaderValue::from_bytes(&combined_value) {
diff --git a/tests/wpt/metadata/fetch/api/headers/headers-combine.html.ini b/tests/wpt/metadata/fetch/api/headers/headers-combine.html.ini
deleted file mode 100644
index 3ecf3b576f7..00000000000
--- a/tests/wpt/metadata/fetch/api/headers/headers-combine.html.ini
+++ /dev/null
@@ -1,14 +0,0 @@
-[headers-combine.html]
-  type: testharness
-  [Create headers using same name for different values]
-    expected: FAIL
-
-  [Check append methods when called with already used name]
-    expected: FAIL
-
-  [Iterate combined values]
-    expected: FAIL
-
-  [Iterate combined values in sorted order]
-    expected: FAIL
-