diff --git a/lib/Twig/Compiler.php b/lib/Twig/Compiler.php
index 2514c31e8..abea3aafe 100644
--- a/lib/Twig/Compiler.php
+++ b/lib/Twig/Compiler.php
@@ -21,7 +21,7 @@ class Twig_Compiler implements Twig_CompilerInterface
     protected $source;
     protected $indentation;
     protected $env;
-    protected $debugInfo;
+    protected $debugInfo = array();
     protected $sourceOffset;
     protected $sourceLine;
     protected $filename;
@@ -34,7 +34,6 @@ class Twig_Compiler implements Twig_CompilerInterface
     public function __construct(Twig_Environment $env)
     {
         $this->env = $env;
-        $this->debugInfo = array();
     }
 
     public function getFilename()
diff --git a/lib/Twig/Environment.php b/lib/Twig/Environment.php
index f68e373d1..7318fe18d 100644
--- a/lib/Twig/Environment.php
+++ b/lib/Twig/Environment.php
@@ -34,15 +34,15 @@ class Twig_Environment
     protected $tests;
     protected $functions;
     protected $globals;
-    protected $runtimeInitialized;
-    protected $extensionInitialized;
+    protected $runtimeInitialized = false;
+    protected $extensionInitialized = false;
     protected $loadedTemplates;
     protected $strictVariables;
     protected $unaryOperators;
     protected $binaryOperators;
     protected $templateClassPrefix = '__TwigTemplate_';
-    protected $functionCallbacks;
-    protected $filterCallbacks;
+    protected $functionCallbacks = array();
+    protected $filterCallbacks = array();
     protected $staging;
 
     /**
@@ -106,15 +106,11 @@ class Twig_Environment
         $this->baseTemplateClass = $options['base_template_class'];
         $this->autoReload = null === $options['auto_reload'] ? $this->debug : (bool) $options['auto_reload'];
         $this->strictVariables = (bool) $options['strict_variables'];
-        $this->runtimeInitialized = false;
         $this->setCache($options['cache']);
-        $this->functionCallbacks = array();
-        $this->filterCallbacks = array();
 
         $this->addExtension(new Twig_Extension_Core());
         $this->addExtension(new Twig_Extension_Escaper($options['autoescape']));
         $this->addExtension(new Twig_Extension_Optimizer($options['optimizations']));
-        $this->extensionInitialized = false;
         $this->staging = new Twig_Extension_Staging();
     }
 
diff --git a/lib/Twig/Extension/Profiler.php b/lib/Twig/Extension/Profiler.php
index 35e04a013..e21fdb6e2 100644
--- a/lib/Twig/Extension/Profiler.php
+++ b/lib/Twig/Extension/Profiler.php
@@ -11,11 +11,11 @@
 
 class Twig_Extension_Profiler extends Twig_Extension
 {
-    private $actives;
+    private $actives = array();
 
     public function __construct(Twig_Profiler_Profile $profile)
     {
-        $this->actives = array($profile);
+        $this->actives[] = $profile;
     }
 
     public function enter(Twig_Profiler_Profile $profile)
diff --git a/lib/Twig/NodeTraverser.php b/lib/Twig/NodeTraverser.php
index 6024e65d0..00f7b54b6 100644
--- a/lib/Twig/NodeTraverser.php
+++ b/lib/Twig/NodeTraverser.php
@@ -19,7 +19,7 @@
 class Twig_NodeTraverser
 {
     protected $env;
-    protected $visitors;
+    protected $visitors = array();
 
     /**
      * Constructor.
@@ -30,7 +30,6 @@ class Twig_NodeTraverser
     public function __construct(Twig_Environment $env, array $visitors = array())
     {
         $this->env = $env;
-        $this->visitors = array();
         foreach ($visitors as $visitor) {
             $this->addVisitor($visitor);
         }
diff --git a/lib/Twig/Template.php b/lib/Twig/Template.php
index cf7c79d2e..e2ab05a24 100644
--- a/lib/Twig/Template.php
+++ b/lib/Twig/Template.php
@@ -22,8 +22,8 @@ abstract class Twig_Template implements Twig_TemplateInterface
     protected $parent;
     protected $parents = array();
     protected $env;
-    protected $blocks;
-    protected $traits;
+    protected $blocks = array();
+    protected $traits = array();
 
     /**
      * Constructor.
@@ -33,8 +33,6 @@ abstract class Twig_Template implements Twig_TemplateInterface
     public function __construct(Twig_Environment $env)
     {
         $this->env = $env;
-        $this->blocks = array();
-        $this->traits = array();
     }
 
     /**
diff --git a/lib/Twig/TokenStream.php b/lib/Twig/TokenStream.php
index 89d2575a8..8d2e220fe 100644
--- a/lib/Twig/TokenStream.php
+++ b/lib/Twig/TokenStream.php
@@ -18,7 +18,7 @@
 class Twig_TokenStream
 {
     protected $tokens;
-    protected $current;
+    protected $current = 0;
     protected $filename;
 
     /**
@@ -30,7 +30,6 @@ class Twig_TokenStream
     public function __construct(array $tokens, $filename = null)
     {
         $this->tokens = $tokens;
-        $this->current = 0;
         $this->filename = $filename;
     }