diff --git a/pyproject.toml b/pyproject.toml
index 46fd8f6b6..f73fbc54f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -35,5 +35,5 @@ dev = [
   "sphinx>=7.2.6,<7.3; python_version >= '3.9'", # for building docs
   "websockets>=13.1",                            # for tests
   # for tests, restrict to exact version for test_http_client/TestClientMockServer/_on_remote_settings_changed that relies on the implementation details. Also, this is no needs to update this package.
-  "h2==4.1.0",
+  "h2==4.3.0",
 ]