diff --git a/include/ada/url_pattern-inl.h b/include/ada/url_pattern-inl.h
index 02e7e085a..c5fa65400 100644
--- a/include/ada/url_pattern-inl.h
+++ b/include/ada/url_pattern-inl.h
@@ -52,7 +52,8 @@ url_pattern_component::create_component_match_result(
     // Let name be component’s group name list[index].
     // Let value be Get(execResult, ToString(index)).
     // Set groups[name] to value.
-    if (auto str = exec_result[index].str(); !str.empty()) {
+    auto match = exec_result[index];
+    if (auto str = match.str(); !str.empty()) {
       result.groups.insert({
           group_name_list[index],
           str,
diff --git a/include/ada/url_pattern.h b/include/ada/url_pattern.h
index 8232221b2..fe2dae060 100644
--- a/include/ada/url_pattern.h
+++ b/include/ada/url_pattern.h
@@ -197,8 +197,11 @@ struct url_pattern_component_result {
 #if ADA_TESTING
   friend void PrintTo(const url_pattern_component_result& result,
                       std::ostream* os) {
-    *os << "input: " << result.input
-        << ", groups_size: " << result.groups.size();
+    *os << "input: '" << result.input
+        << "', group: ";
+    for (const auto& group : result.groups) {
+      *os << "(" << group.first << ", " << group.second << ") ";
+    }
   }
 #endif  // ADA_TESTING
 };
diff --git a/tests/wpt/urlpatterntestdata.json b/tests/wpt/urlpatterntestdata.json
index 9b2c49c2d..6fa7f907d 100644
--- a/tests/wpt/urlpatterntestdata.json
+++ b/tests/wpt/urlpatterntestdata.json
@@ -379,9 +379,8 @@
   {
     "pattern": [{ "pathname": "/foo/:bar?" }],
     "inputs": [{ "pathname": "/foo" }],
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "bar": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
@@ -445,9 +444,8 @@
   {
     "pattern": [{ "pathname": "/foo/:bar*" }],
     "inputs": [{ "pathname": "/foo" }],
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "bar": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
@@ -500,17 +498,15 @@
     "expected_obj": {
       "pathname": "/foo/*?"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "0": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
     "pattern": [{ "pathname": "/foo/*?" }],
     "inputs": [{ "pathname": "/foo" }],
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "0": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
@@ -686,17 +682,15 @@
     "expected_obj": {
       "pathname": "/foo/**"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "0": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
     "pattern": [{ "pathname": "/foo/**" }],
     "inputs": [{ "pathname": "/foo" }],
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "/foo", "groups": { "0": null } }
+      "pathname": { "input": "/foo", "groups": {} }
     }
   },
   {
@@ -1823,10 +1817,9 @@
       "hostname": "(sub.)?example.com",
       "pathname": "/foo"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
       "protocol": { "input": "https", "groups": {} },
-      "hostname": { "input": "example.com", "groups": { "0": null } },
+      "hostname": { "input": "example.com", "groups": {} },
       "pathname": { "input": "/foo", "groups": {} }
     }
   },
@@ -1860,10 +1853,9 @@
       "hostname": "(sub(?:.))?example.com",
       "pathname": "/foo"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
       "protocol": { "input": "https", "groups": {} },
-      "hostname": { "input": "example.com", "groups": { "0": null } },
+      "hostname": { "input": "example.com", "groups": {} },
       "pathname": { "input": "/foo", "groups": {} }
     }
   },
@@ -2295,10 +2287,9 @@
       "protocol": "data",
       "pathname": "text/javascript,let x = 100/:tens?5;"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
       "protocol": { "input": "data", "groups": {} },
-      "pathname": { "input": "text/javascript,let x = 100/5;", "groups": { "tens": null } }
+      "pathname": { "input": "text/javascript,let x = 100/5;", "groups": {} }
     }
   },
   {
@@ -2608,9 +2599,8 @@
     "expected_obj": {
       "pathname": "*(.*)?"
     },
-    "//": "The `null` below is translated to undefined in the test harness.",
     "expected_match": {
-      "pathname": { "input": "foobar", "groups": { "0": "foobar", "1": null }}
+      "pathname": { "input": "foobar", "groups": { "0": "foobar" }}
     }
   },
   {
diff --git a/tests/wpt_urlpattern_tests.cpp b/tests/wpt_urlpattern_tests.cpp
index 0a5a33d90..a9f122e0e 100644
--- a/tests/wpt_urlpattern_tests.cpp
+++ b/tests/wpt_urlpattern_tests.cpp
@@ -304,11 +304,10 @@ ada::url_pattern_component_result parse_component_result(
       ondemand::object groups;
       EXPECT_FALSE(element.value().get_object().get(groups));
       for (auto group : groups) {
-        auto group_key = group.escaped_key().value();
+        auto group_key = group.unescaped_key().value();
         std::string_view group_value;
         EXPECT_FALSE(group.value().get_string(group_value));
-        result.groups.insert_or_assign(std::string(group_key),
-                                       group_value);
+        result.groups.insert_or_assign(std::string(group_key), std::string(group_value));
       }
     }
   }