diff --git a/pkgs/development/python-modules/adext/default.nix b/pkgs/development/python-modules/adext/default.nix
new file mode 100644
index 000000000000..f3818c93188b
--- /dev/null
+++ b/pkgs/development/python-modules/adext/default.nix
@@ -0,0 +1,33 @@
+{ lib
+, buildPythonPackage
+, fetchPypi
+, alarmdecoder
+}:
+
+buildPythonPackage rec {
+  pname = "adext";
+  version = "0.3";
+
+  src = fetchPypi {
+    inherit pname version;
+    sha256 = "184qxw6i5ixnhgkjnby4zwn4jg90mxb8xy9vbg80x5w331p4z50f";
+  };
+
+  postPatch = ''
+    substituteInPlace setup.py \
+      --replace "alarmdecoder==1.13.2" "alarmdecoder>=1.13.2"
+  '';
+
+  propagatedBuildInputs = [ alarmdecoder ];
+
+  # Tests are not published yet
+  doCheck = false;
+  pythonImportsCheck = [ "adext" ];
+
+  meta = with lib; {
+    description = "Python extension for AlarmDecoder";
+    homepage = "https://github.com/ajschmidt8/adext";
+    license = with licenses; [ mit ];
+    maintainers = with maintainers; [ fab ];
+  };
+}
diff --git a/pkgs/servers/home-assistant/component-packages.nix b/pkgs/servers/home-assistant/component-packages.nix
index 558fcf7ab4da..b9a99fa6d271 100644
--- a/pkgs/servers/home-assistant/component-packages.nix
+++ b/pkgs/servers/home-assistant/component-packages.nix
@@ -19,7 +19,7 @@
     "airvisual" = ps: with ps; [ pyairvisual ];
     "aladdin_connect" = ps: with ps; [ ]; # missing inputs: aladdin_connect
     "alarm_control_panel" = ps: with ps; [ ];
-    "alarmdecoder" = ps: with ps; [ ]; # missing inputs: adext
+    "alarmdecoder" = ps: with ps; [ adext ];
     "alert" = ps: with ps; [ ];
     "alexa" = ps: with ps; [ aiohttp-cors ];
     "almond" = ps: with ps; [ aiohttp-cors ]; # missing inputs: pyalmond
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index 912045fa3b9f..073e92cc884a 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -174,6 +174,8 @@ in {
 
   addic7ed-cli = callPackage ../development/python-modules/addic7ed-cli { };
 
+  adext = callPackage ../development/python-modules/adext { };
+
   adguardhome = callPackage ../development/python-modules/adguardhome { };
 
   advantage-air = callPackage ../development/python-modules/advantage-air { };