diff --git a/moli-benchmark/moli_benchmark/wpt_cross/server.py b/moli-benchmark/moli_benchmark/wpt_cross/server.py
index 5b48ccecbf..211252c909 100644
--- a/moli-benchmark/moli_benchmark/wpt_cross/server.py
+++ b/moli-benchmark/moli_benchmark/wpt_cross/server.py
@@ -1157,6 +1157,19 @@ def _xhr_inspect_headers_fixture_response(
     return headers, b"".join(parts)
 
 
+def _workers_url_encoding_response(query: str) -> bytes:
+    """Model workers/semantics/encodings/003-1.py's UTF-8 query check."""
+    value = next(
+        (
+            value
+            for name, value in parse_qsl(query, keep_blank_values=True)
+            if name == "x"
+        ),
+        None,
+    )
+    return b"PASS" if value == "å" else b"FAIL"
+
+
 def _redirect_fixture_response(query: str) -> tuple[int, str] | None:
     """Return the shared redirect response used by static WPT fixture handlers."""
 
@@ -2117,6 +2130,13 @@ def _make_handler(
             if path == "/xhr/resources/delay.py":
                 self._serve_xhr_delay(parsed.query, emit_body=emit_body)
                 return
+            if path == "/workers/semantics/encodings/003-1.py":
+                self._send_bytes(
+                    "text/plain; charset=utf-8",
+                    _workers_url_encoding_response(parsed.query),
+                    emit_body=emit_body,
+                )
+                return
             if path == (
                 "/html/semantics/scripting-1/the-script-element/module/"
                 "resources/delayed-modulescript.py"
diff --git a/moli-benchmark/tests/test_wpt_cross.py b/moli-benchmark/tests/test_wpt_cross.py
index ce759332e6..5cc49feb67 100644
--- a/moli-benchmark/tests/test_wpt_cross.py
+++ b/moli-benchmark/tests/test_wpt_cross.py
@@ -139,6 +139,7 @@ from moli_benchmark.wpt_cross.server import (
     _substitute_wpt_template_variables,
     _window_js_window_wrapper,
     _wasm_webapi_status_code,
+    _workers_url_encoding_response,
     _wpt_delay_seconds,
     _wpt_dedicated_worker_js_wrapper_html,
     _wpt_any_dedicated_worker_wrapper_html,
@@ -4072,6 +4073,44 @@ test(() => {}, "ok");
         self.assertIsNone(_wpt_delay_seconds("ms=-1"))
         self.assertIsNone(_wpt_delay_seconds("ms=nan"))
 
+    def test_fixture_server_models_worker_url_utf8_query_check(self) -> None:
+        self.assertEqual(_workers_url_encoding_response("x=%C3%A5"), b"PASS")
+        self.assertEqual(_workers_url_encoding_response("x=%C3%A5&x=wrong"), b"PASS")
+        self.assertEqual(_workers_url_encoding_response("x=%C3%83%C2%A5"), b"FAIL")
+        self.assertEqual(_workers_url_encoding_response("x=%E5"), b"FAIL")
+        self.assertEqual(_workers_url_encoding_response(""), b"FAIL")
+
+        with tempfile.TemporaryDirectory() as root:
+            root_path = Path(root)
+            (root_path / "resources").mkdir()
+            (root_path / "resources" / "testharness.js").write_text(
+                "// testharness", encoding="utf-8"
+            )
+            with WptFixtureServer(root_path) as server:
+                url = (
+                    f"{server.base_url}/workers/semantics/encodings/"
+                    "003-1.py?x=%C3%A5"
+                )
+                responses = []
+                for method in ("GET", "HEAD"):
+                    with urlopen(Request(url, method=method), timeout=2) as response:
+                        responses.append(
+                            (
+                                method,
+                                response.status,
+                                response.read(),
+                                response.headers["Content-Type"],
+                            )
+                        )
+
+        self.assertEqual(
+            responses,
+            [
+                ("GET", 200, b"PASS", "text/plain; charset=utf-8"),
+                ("HEAD", 200, b"", "text/plain; charset=utf-8"),
+            ],
+        )
+
     def test_fixture_server_models_xhr_delay_py_methods(self) -> None:
         with tempfile.TemporaryDirectory() as root:
             root_path = Path(root)