diff --git a/pkgs/development/python-modules/phart/default.nix b/pkgs/development/python-modules/phart/default.nix
index 44b60a3f7680..23e5d60fc0f2 100644
--- a/pkgs/development/python-modules/phart/default.nix
+++ b/pkgs/development/python-modules/phart/default.nix
@@ -53,6 +53,8 @@ buildPythonPackage rec {
     pydot
   ];
 
+  pytestFlags = [ "-Wignore::DeprecationWarning" ];
+
   pythonImportsCheck = [
     "phart"
   ];