diff --git a/CHANGELOG.md b/CHANGELOG.md
index bc3fa411f8..060013b0f3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,7 @@ Our revised [SSL documentation](docs/advanced/ssl.md) covers how to implement th
 * Ensure `certifi` and `httpcore` are only imported if required. (#3377)
 * Treat `socks5h` as a valid proxy scheme. (#3178)
 * Cleanup `Request()` method signature in line with `client.request()` and `httpx.request()`. (#3378)
+* Bugfix: When passing `params={}`, always strictly update rather than merge with an existing querystring. (#3364)
 
 ## 0.27.2 (27th August, 2024)
 
diff --git a/tests/models/test_requests.py b/tests/models/test_requests.py
index d2a458d57e..b31fe007be 100644
--- a/tests/models/test_requests.py
+++ b/tests/models/test_requests.py
@@ -226,3 +226,16 @@ def content() -> typing.Iterator[bytes]:
     request.read()
     pickle_request = pickle.loads(pickle.dumps(request))
     assert pickle_request.content == b"test 123"
+
+
+def test_request_params():
+    request = httpx.Request("GET", "http://example.com", params={})
+    assert str(request.url) == "http://example.com"
+
+    request = httpx.Request(
+        "GET", "http://example.com?c=3", params={"a": "1", "b": "2"}
+    )
+    assert str(request.url) == "http://example.com?a=1&b=2"
+
+    request = httpx.Request("GET", "http://example.com?a=1", params={})
+    assert str(request.url) == "http://example.com"