diff --git a/pkgs/development/python-modules/mechanize/default.nix b/pkgs/development/python-modules/mechanize/default.nix
index 97fa01697e49..ae9aca2c360a 100644
--- a/pkgs/development/python-modules/mechanize/default.nix
+++ b/pkgs/development/python-modules/mechanize/default.nix
@@ -1,6 +1,7 @@
 {
   lib,
   buildPythonPackage,
+  fetchpatch,
   fetchPypi,
   html5lib,
   pytestCheckHook,
@@ -20,6 +21,14 @@ buildPythonPackage rec {
     hash = "sha256-HeqUf5vn6gq2EPe7xKTja0XWv9/O6imtPTiaiKGVfd8=";
   };
 
+  patches = [
+    (fetchpatch {
+      name = "fix-cookietests-python3.13.patch";
+      url = "https://github.com/python-mechanize/mechanize/commit/0c1cd4b65697dee4e4192902c9a2965d94700502.patch";
+      hash = "sha256-Xlx8ZwHkFbJqeWs+/fllYZt3CZRu9rD8bMHHPuUlRv4=";
+    })
+  ];
+
   build-system = [ setuptools ];
 
   dependencies = [ html5lib ];