diff --git a/changelog.d/11285.misc b/changelog.d/11285.misc
new file mode 100644
index 000000000000..4720519cbc8b
--- /dev/null
+++ b/changelog.d/11285.misc
@@ -0,0 +1 @@
+Require all files in synapse/ and tests/ to pass mypy unless specifically excluded.
diff --git a/mypy.ini b/mypy.ini
index 8c20c293aaad..1752b82bc579 100644
--- a/mypy.ini
+++ b/mypy.ini
@@ -363,6 +363,9 @@ ignore_missing_imports = True
 [mypy-opentracing]
 ignore_missing_imports = True
 
+[mypy-parameterized.*]
+ignore_missing_imports = True
+
 [mypy-phonenumbers.*]
 ignore_missing_imports = True