diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ab47cb6..23a9bac 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11"]
+        python-version: ["3.9", "3.10", "3.11"]
         streamlit-version: [null]
         include:
           # Test with streamlit <1.4.0 and >=1.4.0. See https://github.com/whitphx/streamlit-server-state/issues/64
diff --git a/app_chat_rooms.py b/app_chat_rooms.py
index 136c82e..ec8065d 100644
--- a/app_chat_rooms.py
+++ b/app_chat_rooms.py
@@ -6,7 +6,7 @@
     if "rooms" not in server_state:
         server_state["rooms"] = []
 
-rooms = server_state["rooms"]
+rooms: list[str] = server_state["rooms"]
 
 room = st.sidebar.radio("Select room", rooms)
 
diff --git a/mypy.ini b/mypy.ini
index ad2342c..62825a2 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -1,3 +1,3 @@
 [mypy]
-python_version = 3.8
+python_version = 3.9
 ignore_missing_imports = True