diff --git a/pkgs/development/libraries/java/mockobjects/builder.sh b/pkgs/development/libraries/java/mockobjects/builder.sh
deleted file mode 100755
index fd5d1a20869c..000000000000
--- a/pkgs/development/libraries/java/mockobjects/builder.sh
+++ /dev/null
@@ -1,6 +0,0 @@
-set -e
-source $stdenv/setup
-
-tar xvf $src
-mkdir -p $out
-mv * $out
diff --git a/pkgs/development/libraries/java/mockobjects/default.nix b/pkgs/development/libraries/java/mockobjects/default.nix
index e20d7e707e71..3780ef4abed2 100644
--- a/pkgs/development/libraries/java/mockobjects/default.nix
+++ b/pkgs/development/libraries/java/mockobjects/default.nix
@@ -2,13 +2,24 @@
 
 stdenv.mkDerivation {
   name = "mockobjects-0.09";
-  builder = ./builder.sh;
 
   src = fetchurl {
     url = "mirror://sourceforge/mockobjects/mockobjects-bin-0.09.tar";
     sha256 = "18rnyqfcyh0s3dwkkaszdd50ssyjx5fa1y3ii309ldqg693lfgnz";
   };
 
+  # Work around the "unpacker appears to have produced no directories"
+  setSourceRoot = "sourceRoot=`pwd`";
+
+  installPhase = ''
+    runHook preInstall
+
+    mkdir -p $out/share/java
+    cp mockobjects-*.jar $out/share/java
+
+    runHook postInstall
+  '';
+
   meta = with lib; {
     description = "Generic unit testing framework and methodology for testing any kind of code";
     platforms = platforms.unix;