diff --git a/pkgs/development/python-modules/mnemonic/default.nix b/pkgs/development/python-modules/mnemonic/default.nix
index 839367cc8e31..4250e048430e 100644
--- a/pkgs/development/python-modules/mnemonic/default.nix
+++ b/pkgs/development/python-modules/mnemonic/default.nix
@@ -3,20 +3,23 @@
   buildPythonPackage,
   fetchFromGitHub,
   pytestCheckHook,
+  poetry-core,
 }:
 
 buildPythonPackage rec {
   pname = "mnemonic";
-  version = "0.20";
-  format = "setuptools";
+  version = "0.21";
+  pyproject = true;
 
   src = fetchFromGitHub {
     owner = "trezor";
-    repo = "python-${pname}";
+    repo = "python-mnemonic";
     rev = "v${version}";
-    hash = "sha256-YYgWlYfVd1iALOziaUI8uVYjJDCIVk/dXcUmJd2jcvQ=";
+    hash = "sha256-D1mS/JQhefYmwrShfWR9SdiGsBUM+jmuCkfWix9tDOU=";
   };
 
+  build-system = [ poetry-core ];
+
   nativeCheckInputs = [ pytestCheckHook ];
 
   pythonImportsCheck = [ "mnemonic" ];