diff --git a/pkgs/development/python-modules/kaptan/default.nix b/pkgs/development/python-modules/kaptan/default.nix
index c5f00393839e..309ecda49ccc 100644
--- a/pkgs/development/python-modules/kaptan/default.nix
+++ b/pkgs/development/python-modules/kaptan/default.nix
@@ -16,6 +16,8 @@ buildPythonPackage rec {
 
   postPatch = ''
     sed -i "s/==.*//g" requirements/test.txt
+
+    substituteInPlace requirements/base.txt --replace 'PyYAML>=3.13,<6' 'PyYAML>=3.13'
   '';
 
   propagatedBuildInputs = [ pyyaml ];