diff --git a/conf/templates/pyproject.toml b/conf/templates/pyproject.toml
index c5adcb21..71dc5fa7 100644
--- a/conf/templates/pyproject.toml
+++ b/conf/templates/pyproject.toml
@@ -18,6 +18,8 @@
 
   disallow_incomplete_defs = true
 
+  disallow_untyped_defs = true
+
   enable_error_code = [
     "explicit-override",
     "ignore-without-code",