diff --git a/pkgs/by-name/cf/cfv/package.nix b/pkgs/by-name/cf/cfv/package.nix
index dcac59f78f1d..46d62a01571b 100644
--- a/pkgs/by-name/cf/cfv/package.nix
+++ b/pkgs/by-name/cf/cfv/package.nix
@@ -24,6 +24,7 @@ python3.pkgs.buildPythonApplication rec {
   checkPhase = ''
     runHook preCheck
     cd test
+    ulimit -n 4096
     python3 test.py
     runHook postCheck
   '';