diff --git a/pkgs/development/python-modules/janus/default.nix b/pkgs/development/python-modules/janus/default.nix
index f46ef2e62f5c..c8a9efdb54f8 100644
--- a/pkgs/development/python-modules/janus/default.nix
+++ b/pkgs/development/python-modules/janus/default.nix
@@ -1,4 +1,6 @@
-{ lib, buildPythonPackage, fetchPypi, pytestCheckHook, pythonOlder, pytest-asyncio }:
+{ lib, buildPythonPackage, fetchPypi, pytestCheckHook, pythonOlder, pytest-asyncio
+, typing-extensions
+}:
 
 buildPythonPackage rec {
   pname = "janus";
@@ -11,6 +13,10 @@ buildPythonPackage rec {
 
   disabled = pythonOlder "3.6";
 
+  propagatedBuildInputs = [
+    typing-extensions
+  ];
+
   checkInputs = [ pytest-asyncio pytestCheckHook ];
 
   # also fails upstream: https://github.com/aio-libs/janus/pull/258