diff --git a/pkgs/by-name/he/hepmc2/package.nix b/pkgs/by-name/he/hepmc2/package.nix
index 6944031910ed..fcf852d8f3f5 100644
--- a/pkgs/by-name/he/hepmc2/package.nix
+++ b/pkgs/by-name/he/hepmc2/package.nix
@@ -19,6 +19,7 @@ stdenv.mkDerivation rec {
   cmakeFlags = [
     "-Dmomentum:STRING=GEV"
     "-Dlength:STRING=MM"
+    "-DCMAKE_POLICY_VERSION_MINIMUM=3.5"
   ];
 
   meta = with lib; {