diff --git a/pkgs/by-name/mo/modelscan/package.nix b/pkgs/by-name/mo/modelscan/package.nix
index d506e3d3211d..d6d26b950e93 100644
--- a/pkgs/by-name/mo/modelscan/package.nix
+++ b/pkgs/by-name/mo/modelscan/package.nix
@@ -16,7 +16,10 @@ python3.pkgs.buildPythonApplication (finalAttrs: {
     hash = "sha256-mN2X6Zbai7xm8bdr2hi9fwzIsfQtukeGcOIS32G4hA0=";
   };
 
-  pythonRelaxDeps = [ "rich" ];
+  pythonRelaxDeps = [
+    "rich"
+    "tomlkit"
+  ];
 
   build-system = with python3.pkgs; [
     poetry-core