diff --git a/changelog.d/349.misc b/changelog.d/349.misc
new file mode 100644
index 00000000..997f439c
--- /dev/null
+++ b/changelog.d/349.misc
@@ -0,0 +1 @@
+Bump development dependencies.
diff --git a/mypy.ini b/mypy.ini
index 221bcf20..1f147dd1 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -6,36 +6,9 @@ show_error_codes = True
 show_traceback = True
 mypy_path = stubs
 
-[mypy-idna]
-ignore_missing_imports = True
-
-[mypy-OpenSSL]
-ignore_missing_imports = True
-
-[mypy-twisted.*]
-ignore_missing_imports = True
-
-[mypy-jaeger_client]
-ignore_missing_imports = True
-
-[mypy-aioapns]
-ignore_missing_imports = True
-
-[mypy-aioapns.common]
-ignore_missing_imports = True
-
-[mypy-service_identity.*]
-ignore_missing_imports = True
-
 [mypy-prometheus_client]
 ignore_missing_imports = True
 
-[mypy-setuptools]
-ignore_missing_imports = True
-
-[mypy-OpenSSL.*]
-ignore_missing_imports = True
-
 [mypy-py_vapid]
 ignore_missing_imports = True
 
diff --git a/pyproject.toml b/pyproject.toml
index b55cd96e..87cd223c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -94,15 +94,17 @@ dependencies = [
 
 [project.optional-dependencies]
 dev = [
-    "black==22.3.0",
+    "black==23.9.1",
     "coverage~=5.5",
-    "ruff==0.0.262",
-    "isort~=5.0",
-    "mypy==0.812",
-    "mypy-zope==0.3.0",
+    "ruff==0.0.291",
+    "isort~=5.10",
+    "mypy==1.5.1",
+    "mypy-zope==1.0.1",
     "towncrier",
     "tox",
     "types-opentracing>=2.4.2",
+    "types-pyOpenSSL",
+    "types-PyYAML",
     "typing-extensions>=3.7.4",
 ]
 
diff --git a/sygnal/helper/proxy/proxy_asyncio.py b/sygnal/helper/proxy/proxy_asyncio.py
index 94bbb7ae..31c97659 100644
--- a/sygnal/helper/proxy/proxy_asyncio.py
+++ b/sygnal/helper/proxy/proxy_asyncio.py
@@ -166,6 +166,7 @@ async def switch_over_when_ready(self) -> Tuple[BaseTransport, Protocol]:
 
             # start_tls does NOT call connection_made on new_protocol, so we
             # must do it ourselves
+            assert transport
             buffered_protocol.connection_made(transport)
         else:
             # no wrapping required for non-TLS
@@ -326,7 +327,7 @@ def make_protocol() -> HttpConnectProtocol:
         # (N.B. if we want to ever use TLS to the proxy [e.g. to protect the proxy
         # credentials], we can ask this to give us a TLS connection).
 
-        transport, connect_protocol = await self._wrapped_loop.create_connection(
+        _, connect_protocol = await self._wrapped_loop.create_connection(
             make_protocol, proxy_url_parts.hostname, proxy_url_parts.port
         )
 
diff --git a/sygnal/utils.py b/sygnal/utils.py
index 5d82393d..1cd30f76 100644
--- a/sygnal/utils.py
+++ b/sygnal/utils.py
@@ -43,6 +43,7 @@ class NotificationLoggerAdapter(LoggerAdapter):
     def process(
         self, msg: str, kwargs: MutableMapping[str, Any]
     ) -> Tuple[str, MutableMapping[str, Any]]:
+        assert self.extra
         return f"[{self.extra['request_id']}] {msg}", kwargs
 
 
diff --git a/tests/asyncio_test_helpers.py b/tests/asyncio_test_helpers.py
index 20a7fdf2..32dc7d94 100644
--- a/tests/asyncio_test_helpers.py
+++ b/tests/asyncio_test_helpers.py
@@ -141,7 +141,9 @@ def pause_reading(self) -> None:
     def resume_reading(self) -> None:
         pass  # NOP
 
-    def set_write_buffer_limits(self, high: int = None, low: int = None) -> None:
+    def set_write_buffer_limits(
+        self, high: Optional[int] = None, low: Optional[int] = None
+    ) -> None:
         pass  # NOP
 
     def get_write_buffer_size(self) -> int: