diff --git a/mypy.ini b/mypy.ini
index 7973f2ac01..6590f0c25f 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -75,7 +75,6 @@ exclude = (?x)
    |tests/util/test_lrucache.py
    |tests/util/test_rwlock.py
    |tests/util/test_wheel_timer.py
-   |tests/utils.py
    )$
 
 [mypy-synapse.federation.transport.client]
@@ -129,6 +128,9 @@ disallow_untyped_defs = True
 [mypy-tests.federation.transport.test_client]
 disallow_untyped_defs = True
 
+[mypy-tests.utils]
+disallow_untyped_defs = True
+
 
 ;; Dependencies without annotations
 ;; Before ignoring a module, check to see if type stubs are available.