diff --git a/pkgs/build-support/docker/default.nix b/pkgs/build-support/docker/default.nix
index f16cb7cec13a..731dd1ea9929 100644
--- a/pkgs/build-support/docker/default.nix
+++ b/pkgs/build-support/docker/default.nix
@@ -157,7 +157,7 @@ rec {
         };
         inherit fromImage fromImageName fromImageTag;
 
-        buildInputs = [ utillinux e2fsprogs jshon rsync ];
+        buildInputs = [ utillinux e2fsprogs jshon rsync jq ];
       } ''
       rm -rf $out
 
@@ -202,8 +202,8 @@ rec {
         extractionID=$((extractionID + 1))
 
         mkdir -p image/$extractionID/layer
-        tar -C image/$extractionID/layer -xpf $layerTar
-        rm $layerTar
+        tar -C image/$extractionID/layer -xpf image/$layerTar
+        rm image/$layerTar
 
         find image/$extractionID/layer -name ".wh.*" -exec bash -c 'name="$(basename {}|sed "s/^.wh.//")"; mknod "$(dirname {})/$name" c 0 0; rm {}' \;