diff --git a/bootstrap.sh b/bootstrap.sh
index 57c4bf8..544cdd6 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -1,5 +1,5 @@
 #!/bin/sh -e
 
 php ~/composer.phar install
-php bin/composer2nix --composer-env src/Composer2Nix/composer-env.nix --no-copy-composer-env
+php bin/composer2nix --composer-env src/Composer2Nix/composer-env.nix --no-copy-composer-env --executable
 rm -Rf vendor
diff --git a/php-packages.nix b/php-packages.nix
index 31b29b9..ba66f42 100644
--- a/php-packages.nix
+++ b/php-packages.nix
@@ -5,10 +5,10 @@ let
     "svanderburg/pndp" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "svanderburg-pndp-99b0904e0f2efb35b8f012892912e0d171e9c2da";
+        name = "svanderburg-pndp-4bfe9c4120c23354ab8dc295957dc3009a39bff0";
         src = fetchurl {
-          url = https://api.github.com/repos/svanderburg/pndp/zipball/99b0904e0f2efb35b8f012892912e0d171e9c2da;
-          sha256 = "19l7i7adp76bjf32x9a2ykm0r5cgcmi4wf4cm4127miy3yhs0n4y";
+          url = https://api.github.com/repos/svanderburg/pndp/zipball/4bfe9c4120c23354ab8dc295957dc3009a39bff0;
+          sha256 = "0n2vwpwshv16bhb7a6j95m664zh4lpfa7dqmcyhmn89nxpgvg91y";
         };
       };
     };
@@ -287,20 +287,20 @@ let
     "symfony/config" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-config-0b8541d18507d10204a08384640ff6df3c739ebe";
+        name = "symfony-config-1dbeaa8e2db4b29159265867efff075ad961558c";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/config/zipball/0b8541d18507d10204a08384640ff6df3c739ebe;
-          sha256 = "0ys8afa2n8xbpmj0pnzr1gsgfjx69c81y3mybbp6dn4gnfbd8bch";
+          url = https://api.github.com/repos/symfony/config/zipball/1dbeaa8e2db4b29159265867efff075ad961558c;
+          sha256 = "1wxklsxdxvmbgb5903cl5irgki3yidl61rmxd280r2sfmnyjmdqs";
         };
       };
     };
     "symfony/console" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-console-c0807a2ca978e64d8945d373a9221a5c35d1a253";
+        name = "symfony-console-f81549d2c5fdee8d711c9ab3c7e7362353ea5853";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/console/zipball/c0807a2ca978e64d8945d373a9221a5c35d1a253;
-          sha256 = "1aqnlc10ibzygs0vvpz4hdwrw6xjn42nvn87z6xdggck6jf2z1hn";
+          url = https://api.github.com/repos/symfony/console/zipball/f81549d2c5fdee8d711c9ab3c7e7362353ea5853;
+          sha256 = "02hibfib2gcz959dzlxf1vygghkhlh9lp6x2xfg6dmq2ygbjn0xv";
         };
       };
     };
@@ -317,10 +317,10 @@ let
     "symfony/event-dispatcher" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-event-dispatcher-1377400fd641d7d1935981546aaef780ecd5bf6d";
+        name = "symfony-event-dispatcher-7fe089232554357efb8d4af65ce209fc6e5a2186";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/event-dispatcher/zipball/1377400fd641d7d1935981546aaef780ecd5bf6d;
-          sha256 = "0ky6bmzbwp6frmvz9326d0i1bxzjpvxqhxhi20hq51cmpc63x6c4";
+          url = https://api.github.com/repos/symfony/event-dispatcher/zipball/7fe089232554357efb8d4af65ce209fc6e5a2186;
+          sha256 = "05b4mvacz66gyilnfkksizh1wiy9jsklcs0asn3qvqihxpjg75zl";
         };
       };
     };
@@ -337,40 +337,40 @@ let
     "symfony/finder" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-finder-4f4e84811004e065a3bb5ceeb1d9aa592630f9ad";
+        name = "symfony-finder-a945724b201f74d543e356f6059c930bb8d10c92";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/finder/zipball/4f4e84811004e065a3bb5ceeb1d9aa592630f9ad;
-          sha256 = "1v67z4lhh8471dlfbjrz59rjdxmg036kxxmqyncq8d8n17gyabyf";
+          url = https://api.github.com/repos/symfony/finder/zipball/a945724b201f74d543e356f6059c930bb8d10c92;
+          sha256 = "0bkpdhlnzzvvdxfjsmyy3hq0w5ijj6brppxq40lhli9s8qlwclhc";
         };
       };
     };
     "symfony/polyfill-mbstring" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-polyfill-mbstring-7c8fae0ac1d216eb54349e6a8baa57d515fe8803";
+        name = "symfony-polyfill-mbstring-2ec8b39c38cb16674bbf3fea2b6ce5bf117e1296";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/polyfill-mbstring/zipball/7c8fae0ac1d216eb54349e6a8baa57d515fe8803;
-          sha256 = "1qbin38ca6ivp099wx4cyybdk59r25h2nwsw3vcf4861bcjckbqx";
+          url = https://api.github.com/repos/symfony/polyfill-mbstring/zipball/2ec8b39c38cb16674bbf3fea2b6ce5bf117e1296;
+          sha256 = "0rk5nfgxmr7i1ss67zkm25vk4wpgvhlj11lpsljr6x4400g8f33y";
         };
       };
     };
     "symfony/process" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-process-57e52a0a6a80ea0aec4fc1b785a7920a95cb88a8";
+        name = "symfony-process-26c9fb02bf06bd6b90f661a5bd17e510810d0176";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/process/zipball/57e52a0a6a80ea0aec4fc1b785a7920a95cb88a8;
-          sha256 = "16ip07gg0ghkmmqrdc92n9xlmd106mzky6s5wz2wqgzb4fi98afh";
+          url = https://api.github.com/repos/symfony/process/zipball/26c9fb02bf06bd6b90f661a5bd17e510810d0176;
+          sha256 = "19y1qh7ij5s06lxn4g6gsnxcb61rqjl4gnx2n73jm3hvywlyn7j4";
         };
       };
     };
     "symfony/stopwatch" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-stopwatch-e02577b841394a78306d7b547701bb7bb705bad5";
+        name = "symfony-stopwatch-28ee62ea4736431ca817cdaebcb005663e9cd1cb";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/stopwatch/zipball/e02577b841394a78306d7b547701bb7bb705bad5;
-          sha256 = "06rplxgbadyy0zhjmldwb0n8vmlh2ns4nr63mc9iym3kk8qwcxym";
+          url = https://api.github.com/repos/symfony/stopwatch/zipball/28ee62ea4736431ca817cdaebcb005663e9cd1cb;
+          sha256 = "1mfz0kcdw7y8rklwbhwx2yanrbcc8nynn9jzsssh58j6xwg8vcnq";
         };
       };
     };
@@ -387,10 +387,10 @@ let
     "symfony/validator" = {
       targetDir = "";
       src = composerEnv.buildZipPackage {
-        name = "symfony-validator-864ba6865e253a7ffc3db5629af676cfdc3bd104";
+        name = "symfony-validator-1531ddfd96efd1b2c231cbf45f22e652a8f67925";
         src = fetchurl {
-          url = https://api.github.com/repos/symfony/validator/zipball/864ba6865e253a7ffc3db5629af676cfdc3bd104;
-          sha256 = "0dsgdybk3cypvkidyhrph5qr0cxw51vsc8a0hpjmpkhg04hkc8wd";
+          url = https://api.github.com/repos/symfony/validator/zipball/1531ddfd96efd1b2c231cbf45f22e652a8f67925;
+          sha256 = "0g390pbchvldks2iym2bqxqm5c3gg10fjmmifjsl2wiyx6pxb0lg";
         };
       };
     };
@@ -530,7 +530,7 @@ composerEnv.buildPackage {
   inherit packages devPackages noDev;
   name = "svanderburg-composer2nix";
   src = ./.;
-  executable = false;
+  executable = true;
   symlinkDependencies = false;
   meta = {
     license = "MIT";
diff --git a/src/Composer2Nix/Sources/GitSource.php b/src/Composer2Nix/Sources/GitSource.php
index bac78b5..0a32d76 100644
--- a/src/Composer2Nix/Sources/GitSource.php
+++ b/src/Composer2Nix/Sources/GitSource.php
@@ -9,7 +9,8 @@ use PNDP\AST\NixFunInvocation;
  */
 class GitSource extends Source
 {
-	public $url;
+	/** Stores the output hash of the download */
+	public $hash;
 
 	/**
 	 * Constructs a new Git dependency instance.
diff --git a/src/Composer2Nix/Sources/HgSource.php b/src/Composer2Nix/Sources/HgSource.php
index 32c01ca..9c2c210 100644
--- a/src/Composer2Nix/Sources/HgSource.php
+++ b/src/Composer2Nix/Sources/HgSource.php
@@ -9,6 +9,7 @@ use PNDP\AST\NixFunInvocation;
  */
 class HgSource extends Source
 {
+	/** Stores the output hash of the download */
 	public $hash;
 
 	/**
diff --git a/src/Composer2Nix/Sources/PathSource.php b/src/Composer2Nix/Sources/PathSource.php
index facd5ba..ba40af9 100644
--- a/src/Composer2Nix/Sources/PathSource.php
+++ b/src/Composer2Nix/Sources/PathSource.php
@@ -8,6 +8,7 @@ use PNDP\AST\NixFile;
  */
 class PathSource extends Source
 {
+	/** Path to the file artifact */
 	public $path;
 
 	/**
diff --git a/src/Composer2Nix/Sources/SVNSource.php b/src/Composer2Nix/Sources/SVNSource.php
index 4373849..de9c582 100644
--- a/src/Composer2Nix/Sources/SVNSource.php
+++ b/src/Composer2Nix/Sources/SVNSource.php
@@ -9,6 +9,9 @@ use PNDP\AST\NixFunInvocation;
  */
 class SVNSource extends Source
 {
+	/** Stores the output hash of the download */
+	public $hash;
+
 	/**
 	 * Constructs a new Subversion dependency instance.
 	 *
diff --git a/src/Composer2Nix/Sources/Source.php b/src/Composer2Nix/Sources/Source.php
index 3f965bf..28e2728 100644
--- a/src/Composer2Nix/Sources/Source.php
+++ b/src/Composer2Nix/Sources/Source.php
@@ -9,8 +9,10 @@ use Exception;
  */
 abstract class Source extends NixASTNode
 {
+	/** An array of package configuration properties */
 	public $package;
 
+	/** An array of download properties */
 	protected $sourceObj;
 
 	/**
@@ -53,7 +55,7 @@ abstract class Source extends NixASTNode
 	 *
 	 * @param array $package An array of package configuration properties
 	 * @param string $preferredInstall Preferred installation type (source or dist)
-	 * @return A specific kind of dependency object derived from the source's type
+	 * @return Source A specific kind of dependency object derived from the source's type
 	 * @throw An exception if the type is unrecognized
 	 */
 	public static function constructSource(array $package, $preferredInstall)
diff --git a/src/Composer2Nix/Sources/ZipSource.php b/src/Composer2Nix/Sources/ZipSource.php
index a08ca94..c55942d 100644
--- a/src/Composer2Nix/Sources/ZipSource.php
+++ b/src/Composer2Nix/Sources/ZipSource.php
@@ -11,6 +11,10 @@ use PNDP\AST\NixURL;
  */
 class ZipSource extends Source
 {
+	/* Contains a SHA1 reference to the corresponding Git revision */
+	public $reference;
+
+	/** Stores the output hash of the download */
 	public $hash;
 
 	/**
@@ -30,9 +34,9 @@ class ZipSource extends Source
 	public function fetch()
 	{
 		if($this->sourceObj["reference"] == "")
-			$reference = "";
+			$this->reference = "";
 		else
-			$reference = "-".$this->sourceObj["reference"];
+			$this->reference = "-".$this->sourceObj["reference"];
 
 		if(substr($this->sourceObj["url"], 0, 7) === "http://" || substr($this->sourceObj["url"], 0, 8) === "https://")
 		{
@@ -63,7 +67,7 @@ class ZipSource extends Source
 		}
 
 		$ast["src"] = new NixFunInvocation(new NixExpression("composerEnv.buildZipPackage"), array(
-			"name" => strtr($this->package["name"], "/", "-").$reference,
+			"name" => strtr($this->package["name"], "/", "-").$this->reference,
 			"src" => $src
 		));
 
diff --git a/src/Composer2Nix/composer-env.nix b/src/Composer2Nix/composer-env.nix
index 4528b16..16b1f21 100644
--- a/src/Composer2Nix/composer-env.nix
+++ b/src/Composer2Nix/composer-env.nix
@@ -114,7 +114,8 @@ rec {
 
               if(array_key_exists("bin", $config))
               {
-                  mkdir("vendor/".$binDir);
+                  if(!file_exists("vendor/".$binDir))
+                      mkdir("vendor/".$binDir);
 
                   foreach($config["bin"] as $bin)
                       symlink("../../".$bin, "vendor/".$binDir."/".basename($bin));