diff --git a/pkgs/development/python-modules/pysml/default.nix b/pkgs/development/python-modules/pysml/default.nix
index 5ceb2f290c0..b3a6f195a00 100644
--- a/pkgs/development/python-modules/pysml/default.nix
+++ b/pkgs/development/python-modules/pysml/default.nix
@@ -5,6 +5,7 @@
 , fetchFromGitHub
 , poetry-core
 , pyserial-asyncio
+, pythonOlder
 }:
 
 buildPythonPackage rec {
@@ -12,10 +13,12 @@ buildPythonPackage rec {
   version = "0.0.12";
   format = "pyproject";
 
+  disabled = pythonOlder "3.7";
+
   src = fetchFromGitHub {
     owner = "mtdcr";
     repo = pname;
-    rev = version;
+    rev = "refs/tags/${version}";
     hash = "sha256-DgfTSlgDC92l/hOgrMZrkZi1wzRUDY8tNl4xU3OQgJ8=";
   };
 
@@ -32,7 +35,9 @@ buildPythonPackage rec {
   # Project has no tests
   doCheck = false;
 
-  pythonImportsCheck = [ "sml" ];
+  pythonImportsCheck = [
+    "sml"
+  ];
 
   meta = with lib; {
     description = "Python library for EDL21 smart meters using Smart Message Language (SML)";