diff --git a/pkgs/development/python-modules/trustme/default.nix b/pkgs/development/python-modules/trustme/default.nix
index 6daa99aca6a6..e2ba008d3a0b 100644
--- a/pkgs/development/python-modules/trustme/default.nix
+++ b/pkgs/development/python-modules/trustme/default.nix
@@ -1,4 +1,14 @@
-{ lib, buildPythonPackage, fetchPypi, isPy3k, cryptography, futures, pytest, pyopenssl, service-identity }:
+{ lib
+, buildPythonPackage
+, fetchPypi
+, isPy3k
+, cryptography
+, futures
+, pytest
+, pyopenssl
+, service-identity
+, idna
+}:
 
 buildPythonPackage rec {
   pname = "trustme";
@@ -9,18 +19,25 @@ buildPythonPackage rec {
     sha256 = "103f8n0c60593r0z8hh1zvk1bagxwnhrv3203xpiiddwqxalr04b";
   };
 
-  checkInputs = [ pytest pyopenssl service-identity ];
-  checkPhase = ''
-    py.test
-  '';
+  checkInputs = [
+    pytest
+    pyopenssl
+    service-identity
+  ];
+
   propagatedBuildInputs = [
     cryptography
+    idna
   ] ++ lib.optionals (!isPy3k) [
     futures
   ];
 
+  checkPhase = ''
+    pytest
+  '';
+
   meta = {
-    description = "#1 quality TLS certs while you wait, for the discerning tester";
+    description = "High quality TLS certs while you wait, for the discerning tester";
     homepage = https://github.com/python-trio/trustme;
     license = with lib.licenses; [ mit asl20 ];
     maintainers = with lib.maintainers; [ catern ];