diff --git a/pkgs/development/python-modules/mypy/default.nix b/pkgs/development/python-modules/mypy/default.nix
index 5dad7136d271..ffdd8bc5ac2c 100644
--- a/pkgs/development/python-modules/mypy/default.nix
+++ b/pkgs/development/python-modules/mypy/default.nix
@@ -120,6 +120,7 @@ buildPythonPackage rec {
     ];
 
   passthru.tests = {
+    # Failing typing checks on the test-driver result in channel blockers.
     inherit (nixosTests) nixos-test-driver;
   };