diff --git a/pkgs/development/python-modules/testing-postgresql/default.nix b/pkgs/development/python-modules/testing-postgresql/default.nix
index 1b1527cc4872..c2b85fe8f9d7 100644
--- a/pkgs/development/python-modules/testing-postgresql/default.nix
+++ b/pkgs/development/python-modules/testing-postgresql/default.nix
@@ -46,6 +46,8 @@ buildPythonPackage rec {
   postPatch = ''
     substituteInPlace setup.py \
       --replace "pg8000 >= 1.10" "pg8000"
+    substituteInPlace tests/test_postgresql.py \
+      --replace-fail "self.assertRegexpMatches" "self.assertRegex"
   '';
 
   pythonImportsCheck = [ "testing.postgresql" ];