diff --git a/pkgs/by-name/or/orcania/package.nix b/pkgs/by-name/or/orcania/package.nix
index 14cc99622755..e0e3775531df 100644
--- a/pkgs/by-name/or/orcania/package.nix
+++ b/pkgs/by-name/or/orcania/package.nix
@@ -16,6 +16,12 @@ stdenv.mkDerivation rec {
 
   cmakeFlags = [ "-DBUILD_ORCANIA_TESTING=on" ];
 
+  env.NIX_CFLAGS_COMPILE = toString (
+    lib.optionals stdenv.cc.isClang [
+      "-Wno-error=constant-conversion"
+    ]
+  );
+
   doCheck = true;
 
   meta = with lib; {