diff --git a/pkgs/development/python-modules/marshmallow-dataclass/default.nix b/pkgs/development/python-modules/marshmallow-dataclass/default.nix
index 1638fb33e17a..0adc51e2155d 100644
--- a/pkgs/development/python-modules/marshmallow-dataclass/default.nix
+++ b/pkgs/development/python-modules/marshmallow-dataclass/default.nix
@@ -2,6 +2,7 @@
   lib,
   buildPythonPackage,
   fetchFromGitHub,
+  fetchpatch,
   marshmallow,
   pytestCheckHook,
   setuptools,
@@ -21,6 +22,15 @@ buildPythonPackage rec {
     hash = "sha256-0OXP78oyNe/UcI05NHskPyXAuX3dwAW4Uz4dI4b8KV0=";
   };
 
+  patches = [
+    # Fix test_set_only_work_in_hashable_types on Python 3.14, https://github.com/lovasoa/marshmallow_dataclass/pull/286
+    (fetchpatch {
+      name = "fix-test.patch";
+      url = "https://github.com/lovasoa/marshmallow_dataclass/commit/9a2ea19924a3cd5fadeb41663bfca64b9c0f75e4.patch";
+      hash = "sha256-T2UbZdCj4+HRglMp8w3kU20sUcN6WoSyKiLNr1kSius=";
+    })
+  ];
+
   build-system = [ setuptools ];
 
   dependencies = [
@@ -52,4 +62,4 @@ buildPythonPackage rec {
     license = lib.licenses.mit;
     maintainers = with lib.maintainers; [ fab ];
   };
-}
+})