diff --git a/pkgs/development/python-modules/pytest-mock/default.nix b/pkgs/development/python-modules/pytest-mock/default.nix
index 68c16725cd4..8fba5e90ab1 100644
--- a/pkgs/development/python-modules/pytest-mock/default.nix
+++ b/pkgs/development/python-modules/pytest-mock/default.nix
@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi, isPy3k, pytest, mock, setuptools_scm }:
+{ lib, buildPythonPackage, fetchPypi, fetchpatch, isPy3k, pytest, mock, setuptools_scm }:
 
 buildPythonPackage rec {
   pname = "pytest-mock";
@@ -12,6 +12,14 @@ buildPythonPackage rec {
   propagatedBuildInputs = lib.optional (!isPy3k) mock;
   nativeBuildInputs = [ setuptools_scm pytest ];
 
+  patches = [
+    # Fix tests for pytest 4.6. Remove with the next release
+    (fetchpatch {
+      url = "https://github.com/pytest-dev/pytest-mock/commit/189cc599d3bfbe91a17c93211c04237b6c5849b1.patch";
+      sha256 = "13nk75ldab3j8nfzyd9w4cgfk2fxq4if1aqkqy82ar7y7qh07a7m";
+    })
+  ];
+
   checkPhase = ''
     py.test
   '';