diff --git a/pkgs/development/python-modules/three-merge/default.nix b/pkgs/development/python-modules/three-merge/default.nix
index c6279b9d9226..37d3cabdf405 100644
--- a/pkgs/development/python-modules/three-merge/default.nix
+++ b/pkgs/development/python-modules/three-merge/default.nix
@@ -1,9 +1,10 @@
 {
   lib,
   buildPythonPackage,
-  fetchPypi,
+  fetchFromGitHub,
   setuptools,
   diff-match-patch,
+  pytestCheckHook,
 }:
 
 buildPythonPackage (finalAttrs: {
@@ -13,16 +14,20 @@ buildPythonPackage (finalAttrs: {
 
   __structuredAttrs = true;
 
-  src = fetchPypi {
-    pname = "three-merge";
-    inherit (finalAttrs) version;
-    hash = "sha256-YPav4URZVWDWOuMmJTUbzvO5RzO1Trl4AKn+sPPZ2XA=";
+  # pypi does not contain test files
+  src = fetchFromGitHub {
+    owner = "spyder-ide";
+    repo = "three-merge";
+    tag = "v${finalAttrs.version}";
+    hash = "sha256-BtWgBOSddLB7mQoc8vhGKxBBkdnvyASyrwRLA7lGgrs=";
   };
 
   build-system = [ setuptools ];
 
   dependencies = [ diff-match-patch ];
 
+  nativeCheckInputs = [ pytestCheckHook ];
+
   pythonImportsCheck = [ "three_merge" ];
 
   meta = {