diff --git a/pkgs/tools/admin/simp_le/default.nix b/pkgs/tools/admin/simp_le/default.nix
index 91d0ba360168..9b6cd8fe5c9c 100644
--- a/pkgs/tools/admin/simp_le/default.nix
+++ b/pkgs/tools/admin/simp_le/default.nix
@@ -1,12 +1,18 @@
-{ lib, python3Packages, fetchPypi, bash }:
+{
+  lib,
+  python3Packages,
+  fetchPypi,
+  bash,
+}:
 
 python3Packages.buildPythonApplication rec {
   pname = "simp_le-client";
   version = "0.20.0";
+  pyproject = true;
 
   src = fetchPypi {
     inherit pname version;
-    sha256 = "sha256-p6+OF8MuAzcdTV4/CvZpjGaOrg7xcNuEddk7yC2sXIE=";
+    hash = "sha256-p6+OF8MuAzcdTV4/CvZpjGaOrg7xcNuEddk7yC2sXIE=";
   };
 
   postPatch = ''
@@ -16,19 +22,33 @@ python3Packages.buildPythonApplication rec {
       --replace "/bin/sh" "${bash}/bin/sh"
   '';
 
+  # both setuptools-scm and mock are runtime dependencies
+  dependencies = with python3Packages; [
+    acme
+    cryptography
+    setuptools-scm
+    josepy
+    idna
+    mock
+    pyopenssl
+    pytz
+    six
+  ];
+
   checkPhase = ''
+    runHook preCheck
     $out/bin/simp_le --test
+    runHook postCheck
   '';
 
-  propagatedBuildInputs = with python3Packages; [ acme setuptools-scm josepy idna ];
-
-  nativeCheckInputs = with python3Packages; [ mock ];
-
   meta = with lib; {
     homepage = "https://github.com/zenhack/simp_le";
     description = "Simple Let's Encrypt client";
     license = licenses.gpl3;
-    maintainers = with maintainers; [ gebner makefu ];
+    maintainers = with maintainers; [
+      gebner
+      makefu
+    ];
     platforms = platforms.linux;
   };
 }