diff --git a/mkClojureLib.nix b/mkClojureLib.nix
index 877a557..20e667f 100644
--- a/mkClojureLib.nix
+++ b/mkClojureLib.nix
@@ -27,21 +27,23 @@ in stdenv.mkDerivation {
   nativeBuildInputs = [ clojure jre ];
   buildInputs = (map (x: x.paths) clj-deps.packages);
 
-  buildPhase = ''
-    HOME=$TEMP/home
-    mkdir -p $HOME
-    mkdir -p ${target}
+  buildPhase = let
+    script = writeShellScript "create-uberjar.sh" ''
+      HOME=$TEMP/home
+      mkdir -p $HOME
+      mkdir -p ${target}
 
-    clojure \
-      -Scp     .:${build-tools-jar}:${classpath} \
-      -Sdeps   ${builtins.trace build-tools-deps build-tools-deps} \
-      -X:build \
-      lib-uberjar \
-      :project ${group}/${name} \
-      :version ${version} \
-      :srcs    ${concatStringsSep "," src-paths} \
-      :target  ${target}
-  '';
+      clojure \
+        -Scp     .:${build-tools-jar}:${classpath} \
+        -Sdeps   ${builtins.trace build-tools-deps build-tools-deps} \
+        -X:build \
+        lib-uberjar \
+        :project ${group}/${name} \
+        :version ${version} \
+        :srcs    ${concatStringsSep "," src-paths} \
+        :target  ${target}
+    '';
+  in "${builtins.trace script script}";
 
   installPhase = ''
     mv ${target}/${name}-${version}-standalone.jar $out