diff --git a/pyproject.toml b/pyproject.toml
index f5dbb25..d56c363 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -17,7 +17,7 @@ classifiers = [
     "Typing :: Typed",
     "Topic :: Software Development :: Libraries",
 ]
-dependencies = ["flask>=3,<4", "modern-di>=3.1,<4"]
+dependencies = ["flask>=3,<4", "modern-di>=4,<5"]
 version = "0"
 
 [project.urls]
diff --git a/tests/conftest.py b/tests/conftest.py
index ca59e40..4130d8a 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -16,6 +16,6 @@ def app() -> Flask:
 
 @pytest.fixture
 def container() -> typing.Iterator[Container]:
-    # caller owns opening the root container under modern-di 3.x's mandatory-open lifecycle
+    # caller owns opening the root container under modern-di's mandatory-open lifecycle
     with Container(groups=[Dependencies]) as container_:
         yield container_
diff --git a/tests/dependencies.py b/tests/dependencies.py
index c2f9da1..a8b4ea0 100644
--- a/tests/dependencies.py
+++ b/tests/dependencies.py
@@ -14,11 +14,8 @@ class DependentCreator:
     dep1: SimpleCreator
 
 
-def fetch_request_path(request: flask.Request | None = None) -> str:
-    # Optional-with-default so an explicit container.validate() treats the request
-    # as optional (the provider is only registered by setup_di); the real request
-    # still injects at runtime.
-    return request.path if request else ""
+def fetch_request_path(request: flask.Request) -> str:
+    return request.path
 
 
 class Dependencies(Group):