diff --git a/pkgs/build-support/trivial-builders/default.nix b/pkgs/build-support/trivial-builders/default.nix
index 871f9722a4a2..9099a38b75b3 100644
--- a/pkgs/build-support/trivial-builders/default.nix
+++ b/pkgs/build-support/trivial-builders/default.nix
@@ -87,6 +87,8 @@ rec {
       inherit buildCommand name;
       passAsFile = [ "buildCommand" ]
         ++ (derivationArgs.passAsFile or []);
+    }
+    // lib.optionalAttrs (! derivationArgs?meta) {
       pos = let args = builtins.attrNames derivationArgs; in
         if builtins.length args > 0
         then builtins.unsafeGetAttrPos (builtins.head args) derivationArgs