1 files changed, 1 insertions, 0 deletions

diff --git a/mypy.ini b/mypy.ini

index 7986781432..c283f15b21 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -6,6 +6,7 @@ check_untyped_defs = True
 show_error_codes = True
 show_traceback = True
 mypy_path = stubs
+warn_unreachable = True
 files =
   synapse/api,
   synapse/appservice,