diff --git a/pkgs/development/python-modules/python-datemath/default.nix b/pkgs/development/python-modules/python-datemath/default.nix
index 4b0366ae4da5..0dc6b6034532 100644
--- a/pkgs/development/python-modules/python-datemath/default.nix
+++ b/pkgs/development/python-modules/python-datemath/default.nix
@@ -2,9 +2,9 @@
 , arrow
 , buildPythonPackage
 , fetchFromGitHub
+, fetchpatch
 , pythonOlder
 , pytestCheckHook
-, unittest2
 }:
 
 buildPythonPackage rec {
@@ -21,13 +21,20 @@ buildPythonPackage rec {
     sha256 = "sha256-WVWGhyBguE1+KEMQu0N5QxO7IC4rPEJ/2L3VWUCQNi4=";
   };
 
+  patches = [
+    (fetchpatch {
+      name = "remove-unittest2.patch";
+      url = "https://github.com/nickmaccarthy/python-datemath/commit/781daa0241ed327d5f211f3b62f553f3ee3d86e0.patch";
+      hash = "sha256-WD6fuDaSSNXgYWoaUexiWnofCzEZzercEUlqTvOUT5I=";
+    })
+  ];
+
   propagatedBuildInputs = [
     arrow
   ];
 
   checkInputs = [
     pytestCheckHook
-    unittest2
   ];
 
   pytestFlagsArray = [