diff --git a/pkgs/data/machine-learning/mnist/default.nix b/pkgs/data/machine-learning/mnist/default.nix
index f5b450b4f2ad..b4c4d43e99ae 100644
--- a/pkgs/data/machine-learning/mnist/default.nix
+++ b/pkgs/data/machine-learning/mnist/default.nix
@@ -29,7 +29,7 @@ in
       ln -s "${srcs.test-images}" "$out/${srcs.test-images.name}"
       ln -s "${srcs.test-labels}" "$out/${srcs.test-labels.name}"
     '';
-    phases = [ "installPhase" ];
+    dontUnpack = true;
     meta = with lib; {
       description = "A large database of handwritten digits";
       longDescription = ''