diff --git a/pkgs/by-name/sn/snakefmt/package.nix b/pkgs/by-name/sn/snakefmt/package.nix
index b2972cd6697e..44735da75e42 100644
--- a/pkgs/by-name/sn/snakefmt/package.nix
+++ b/pkgs/by-name/sn/snakefmt/package.nix
@@ -27,6 +27,8 @@ python3.pkgs.buildPythonApplication rec {
     toml
   ];
 
+  pythonRelaxDeps = [ "black" ];
+
   pythonImportsCheck = [ "snakefmt" ];
 
   nativeInstallCheckInputs = [ versionCheckHook ];