diff --git a/nixos/lib/systemd-lib.nix b/nixos/lib/systemd-lib.nix
index 5669aae0bc19..fc95ab01289f 100644
--- a/nixos/lib/systemd-lib.nix
+++ b/nixos/lib/systemd-lib.nix
@@ -21,11 +21,12 @@ in rec {
         { preferLocalBuild = true;
           allowSubstitutes = false;
           inherit (unit) text;
+          passAsFile = [ "text" ];
         }
         ''
           name=${shellEscape name}
           mkdir -p "$out/$(dirname -- "$name")"
-          echo -n "$text" > "$out/$name"
+          mv "$textPath" "$out/$name"
         ''
     else
       pkgs.runCommand "unit-${mkPathSafeName name}-disabled"