diff --git a/homeassistant/components/tasmota/discovery.py b/homeassistant/components/tasmota/discovery.py
index 92fcbcc7fc4..44a1ac9e38b 100644
--- a/homeassistant/components/tasmota/discovery.py
+++ b/homeassistant/components/tasmota/discovery.py
@@ -248,6 +248,7 @@ async def async_start(  # noqa: C901
 
         if not payload:
             return
+        assert isinstance(command_topic, str)
 
         # Warn and add issues if there are duplicated topics
         if warn_if_topic_duplicated(hass, command_topic, mac, tasmota_device_config):
diff --git a/requirements_test.txt b/requirements_test.txt
index b5bba1def11..d8ca408940e 100644
--- a/requirements_test.txt
+++ b/requirements_test.txt
@@ -11,7 +11,7 @@ astroid==3.2.2
 coverage==7.5.3
 freezegun==1.5.0
 mock-open==1.4.0
-mypy-dev==1.11.0a9
+mypy-dev==1.12.0a1
 pre-commit==3.7.1
 pydantic==1.10.17
 pylint==3.2.4
diff --git a/script/hassfest/mypy_config.py b/script/hassfest/mypy_config.py
index 56734257f78..d2aff81aa05 100644
--- a/script/hassfest/mypy_config.py
+++ b/script/hassfest/mypy_config.py
@@ -36,7 +36,7 @@ GENERAL_SETTINGS: Final[dict[str, str]] = {
     "plugins": "pydantic.mypy",
     "show_error_codes": "true",
     "follow_imports": "normal",
-    "enable_incomplete_feature": ",".join(  # noqa: FLY002
+    "enable_incomplete_feature": ", ".join(  # noqa: FLY002
         [
             "NewGenericSyntax",
         ]