diff --git a/pkgs/development/python-modules/pyzx/default.nix b/pkgs/development/python-modules/pyzx/default.nix
index d39d2b48ef24..27371dc2bbd6 100644
--- a/pkgs/development/python-modules/pyzx/default.nix
+++ b/pkgs/development/python-modules/pyzx/default.nix
@@ -38,7 +38,10 @@ buildPythonPackage rec {
     typing-extensions
   ];
 
-  pythonRelaxDeps = [ "ipywidgets" ];
+  pythonRelaxDeps = [
+    "ipywidgets"
+    "lark"
+  ];
 
   nativeCheckInputs = [ pytestCheckHook ];
   disabledTestPaths = [