diff --git a/pkgs/development/tools/ammonite/default.nix b/pkgs/development/tools/ammonite/default.nix
index 680217acfbb..ffd3b78cedd 100644
--- a/pkgs/development/tools/ammonite/default.nix
+++ b/pkgs/development/tools/ammonite/default.nix
@@ -17,7 +17,7 @@ let
         inherit sha256;
       };
 
-      phases = "installPhase";
+      dontUnpack = true;
 
       installPhase = ''
         install -Dm755 $src $out/bin/amm