diff --git a/pkgs/development/python-modules/fava/default.nix b/pkgs/development/python-modules/fava/default.nix
index ee8579128317..2d26a16dc772 100644
--- a/pkgs/development/python-modules/fava/default.nix
+++ b/pkgs/development/python-modules/fava/default.nix
@@ -2,7 +2,6 @@
   lib,
   buildPythonPackage,
   buildNpmPackage,
-  fetchpatch2,
   fetchFromGitHub,
   stdenv,
   babel,
@@ -84,6 +83,8 @@ buildPythonPackage {
     watchfiles
   ];
 
+  pythonRelaxDeps = [ "simplejson" ];
+
   nativeCheckInputs = [ pytestCheckHook ];
 
   pythonImportsCheck = [ "fava" ];