diff --git a/example/Server.php b/example/Server.php
index 6ea97018..eaf9d7ea 100644
--- a/example/Server.php
+++ b/example/Server.php
@@ -11,9 +11,7 @@
 
 namespace Leafo\ScssPhp;
 
-use Leafo\ScssPhp\Compiler;
 use Leafo\ScssPhp\Exception\ServerException;
-use Leafo\ScssPhp\Version;
 
 /**
  * Server
@@ -468,7 +466,7 @@ public function cachedCompile($in, $force = false)
 
         if ($root !== null) {
             // If we have a root value which means we should rebuild.
-            $out = array();
+            $out = [];
             $out['root'] = $root;
             $out['compiled'] = $this->compileFile($root);
             $out['files'] = $this->scss->getParsedFiles();
diff --git a/src/Compiler.php b/src/Compiler.php
index 637f1c1c..56b463ec 100644
--- a/src/Compiler.php
+++ b/src/Compiler.php
@@ -12,16 +12,10 @@
 namespace Leafo\ScssPhp;
 
 use Leafo\ScssPhp\Base\Range;
-use Leafo\ScssPhp\Block;
-use Leafo\ScssPhp\Colors;
 use Leafo\ScssPhp\Compiler\Environment;
 use Leafo\ScssPhp\Exception\CompilerException;
 use Leafo\ScssPhp\Formatter\OutputBlock;
-use Leafo\ScssPhp\Node;
 use Leafo\ScssPhp\SourceMap\SourceMapGenerator;
-use Leafo\ScssPhp\Type;
-use Leafo\ScssPhp\Parser;
-use Leafo\ScssPhp\Util;
 
 /**
  * The scss compiler and parser.
@@ -1308,7 +1302,7 @@ protected function hasSelectorPlaceholder($selector)
      * @param array                                $stms
      * @param \Leafo\ScssPhp\Formatter\OutputBlock $out
      *
-     * @return array
+     * @return array|null
      */
     protected function compileChildren($stms, OutputBlock $out)
     {
@@ -1319,6 +1313,7 @@ protected function compileChildren($stms, OutputBlock $out)
                 return $ret;
             }
         }
+        return null;
     }
 
     /**
@@ -2004,7 +1999,7 @@ protected function shouldEval($value)
         switch ($value[0]) {
             case Type::T_EXPRESSION:
                 if ($value[1] === '/') {
-                    return $this->shouldEval($value[2], $value[3]);
+                    return $this->shouldEval($value[2]);
                 }
 
                 // fall-thru
@@ -2366,7 +2361,7 @@ protected function opModNumberNumber($left, $right)
      * @param array $left
      * @param array $right
      *
-     * @return array
+     * @return array|null
      */
     protected function opAdd($left, $right)
     {
@@ -2389,6 +2384,7 @@ protected function opAdd($left, $right)
 
             return $strRight;
         }
+        return null;
     }
 
     /**
@@ -2398,12 +2394,12 @@ protected function opAdd($left, $right)
      * @param array   $right
      * @param boolean $shouldEval
      *
-     * @return array
+     * @return array|null
      */
     protected function opAnd($left, $right, $shouldEval)
     {
         if (! $shouldEval) {
-            return;
+            return null;
         }
 
         if ($left !== static::$false and $left !== static::$null) {
@@ -2420,12 +2416,12 @@ protected function opAnd($left, $right, $shouldEval)
      * @param array   $right
      * @param boolean $shouldEval
      *
-     * @return array
+     * @return array|null
      */
     protected function opOr($left, $right, $shouldEval)
     {
         if (! $shouldEval) {
-            return;
+            return null;
         }
 
         if ($left !== static::$false and $left !== static::$null) {
@@ -3158,7 +3154,7 @@ protected function setRaw($name, $value, Environment $env)
      * @param boolean                             $shouldThrow
      * @param \Leafo\ScssPhp\Compiler\Environment $env
      *
-     * @return mixed
+     * @return mixed|null
      */
     public function get($name, $shouldThrow = true, Environment $env = null)
     {
@@ -3200,6 +3196,7 @@ public function get($name, $shouldThrow = true, Environment $env = null)
         }
 
         // found nothing
+        return null;
     }
 
     /**
@@ -3528,6 +3525,7 @@ public function setEncoding($encoding)
     public function setIgnoreErrors($ignoreErrors)
     {
         $this->ignoreErrors = $ignoreErrors;
+        return $this;
     }
 
     /**
@@ -4925,7 +4923,7 @@ protected function libSetNth($args)
         if (! isset($list[2][$n])) {
             $this->throwError('Invalid argument for "n"');
 
-            return;
+            return null;
         }
 
         $list[2][$n] = $args[2];
@@ -5163,7 +5161,7 @@ protected function libComparable($args)
         ) {
             $this->throwError('Invalid argument(s) for "comparable"');
 
-            return;
+            return null;
         }
 
         $number1 = $number1->normalize();
@@ -5343,7 +5341,7 @@ protected function libRandom($args)
             if ($n < 1) {
                 $this->throwError("limit must be greater than or equal to 1");
 
-                return;
+                return null;
             }
 
             return new Node\Number(mt_rand(1, $n), '');
diff --git a/src/Formatter/Compressed.php b/src/Formatter/Compressed.php
index 1faa7e11..8d86210c 100644
--- a/src/Formatter/Compressed.php
+++ b/src/Formatter/Compressed.php
@@ -12,7 +12,6 @@
 namespace Leafo\ScssPhp\Formatter;
 
 use Leafo\ScssPhp\Formatter;
-use Leafo\ScssPhp\Formatter\OutputBlock;
 
 /**
  * Compressed formatter
diff --git a/src/Formatter/Crunched.php b/src/Formatter/Crunched.php
index 42d77b5f..4569b4e2 100644
--- a/src/Formatter/Crunched.php
+++ b/src/Formatter/Crunched.php
@@ -12,7 +12,6 @@
 namespace Leafo\ScssPhp\Formatter;
 
 use Leafo\ScssPhp\Formatter;
-use Leafo\ScssPhp\Formatter\OutputBlock;
 
 /**
  * Crunched formatter
diff --git a/src/Formatter/Debug.php b/src/Formatter/Debug.php
index bfcbf41a..089c7987 100644
--- a/src/Formatter/Debug.php
+++ b/src/Formatter/Debug.php
@@ -12,7 +12,6 @@
 namespace Leafo\ScssPhp\Formatter;
 
 use Leafo\ScssPhp\Formatter;
-use Leafo\ScssPhp\Formatter\OutputBlock;
 
 /**
  * Debug formatter
diff --git a/src/Formatter/Expanded.php b/src/Formatter/Expanded.php
index d8c1e887..10e4225d 100644
--- a/src/Formatter/Expanded.php
+++ b/src/Formatter/Expanded.php
@@ -12,7 +12,6 @@
 namespace Leafo\ScssPhp\Formatter;
 
 use Leafo\ScssPhp\Formatter;
-use Leafo\ScssPhp\Formatter\OutputBlock;
 
 /**
  * Expanded formatter
diff --git a/src/Formatter/Nested.php b/src/Formatter/Nested.php
index 8f72206f..d43cb4fd 100644
--- a/src/Formatter/Nested.php
+++ b/src/Formatter/Nested.php
@@ -12,7 +12,6 @@
 namespace Leafo\ScssPhp\Formatter;
 
 use Leafo\ScssPhp\Formatter;
-use Leafo\ScssPhp\Formatter\OutputBlock;
 
 /**
  * Nested formatter
diff --git a/src/Parser.php b/src/Parser.php
index 748d38ae..c3f63c91 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -11,11 +11,7 @@
 
 namespace Leafo\ScssPhp;
 
-use Leafo\ScssPhp\Block;
-use Leafo\ScssPhp\Compiler;
 use Leafo\ScssPhp\Exception\ParserException;
-use Leafo\ScssPhp\Node;
-use Leafo\ScssPhp\Type;
 
 /**
  * Parser
@@ -1174,7 +1170,7 @@ protected function genericList(&$out, $parseItem, $delim = '', $flatten = true)
     {
         $s = $this->seek();
         $items = [];
-
+        $value = null;
         while ($this->$parseItem($value)) {
             $items[] = $value;
 
diff --git a/src/SourceMap/Base64.php b/src/SourceMap/Base64.php
index 9d17e6f0..54015bb9 100644
--- a/src/SourceMap/Base64.php
+++ b/src/SourceMap/Base64.php
@@ -21,7 +21,7 @@ class Base64
     /**
      * @var array
      */
-    private static $encodingMap = array (
+    private static $encodingMap = [
         0 => 'A',
         1 => 'B',
         2 => 'C',
@@ -86,12 +86,12 @@ class Base64
         61 => '9',
         62 => '+',
         63 => '/',
-    );
+    ];
 
     /**
      * @var array
      */
-    private static $decodingMap = array(
+    private static $decodingMap = [
         'A' => 0,
         'B' => 1,
         'C' => 2,
@@ -156,7 +156,7 @@ class Base64
         9 => 61,
         '+' => 62,
         '/' => 63,
-    );
+    ];
 
     /**
      * Convert to base64
diff --git a/src/SourceMap/Base64VLQ.php b/src/SourceMap/Base64VLQ.php
index 6de3b5ee..9f617f7b 100644
--- a/src/SourceMap/Base64VLQ.php
+++ b/src/SourceMap/Base64VLQ.php
@@ -11,8 +11,6 @@
 
 namespace Leafo\ScssPhp\SourceMap;
 
-use Leafo\ScssPhp\SourceMap\Base64;
-
 /**
  * Base 64 VLQ
  *
diff --git a/src/SourceMap/Base64VLQEncoder.php b/src/SourceMap/Base64VLQEncoder.php
index 1189ce0e..caf56c77 100644
--- a/src/SourceMap/Base64VLQEncoder.php
+++ b/src/SourceMap/Base64VLQEncoder.php
@@ -47,7 +47,7 @@ class Base64VLQEncoder
      *
      * @var array
      */
-    private $charToIntMap = array(
+    private $charToIntMap = [
         'A' => 0,  'B' => 1,  'C' => 2,  'D' => 3,  'E' => 4,  'F' => 5,  'G' => 6,  'H' => 7,
         'I' => 8,  'J' => 9,  'K' => 10, 'L' => 11, 'M' => 12, 'N' => 13, 'O' => 14, 'P' => 15,
         'Q' => 16, 'R' => 17, 'S' => 18, 'T' => 19, 'U' => 20, 'V' => 21, 'W' => 22, 'X' => 23,
@@ -56,14 +56,14 @@ class Base64VLQEncoder
         'o' => 40, 'p' => 41, 'q' => 42, 'r' => 43, 's' => 44, 't' => 45, 'u' => 46, 'v' => 47,
         'w' => 48, 'x' => 49, 'y' => 50, 'z' => 51,   0 => 52,   1 => 53,   2 => 54,   3 => 55,
           4 => 56,   5 => 57,   6 => 58,   7 => 59,   8 => 60,   9 => 61, '+' => 62, '/' => 63,
-    );
+    ];
 
     /**
      * Integer to char map
      *
      * @var array
      */
-    private $intToCharMap = array(
+    private $intToCharMap = [
          0 => 'A',  1 => 'B',  2 => 'C',  3 => 'D',  4 => 'E',  5 => 'F',  6 => 'G',  7 => 'H',
          8 => 'I',  9 => 'J', 10 => 'K', 11 => 'L', 12 => 'M', 13 => 'N', 14 => 'O', 15 => 'P',
         16 => 'Q', 17 => 'R', 18 => 'S', 19 => 'T', 20 => 'U', 21 => 'V', 22 => 'W', 23 => 'X',
@@ -72,7 +72,7 @@ class Base64VLQEncoder
         40 => 'o', 41 => 'p', 42 => 'q', 43 => 'r', 44 => 's', 45 => 't', 46 => 'u', 47 => 'v',
         48 => 'w', 49 => 'x', 50 => 'y', 51 => 'z', 52 => '0', 53 => '1', 54 => '2', 55 => '3',
         56 => '4', 57 => '5', 58 => '6', 59 => '7', 60 => '8', 61 => '9', 62 => '+', 63 => '/',
-    );
+    ];
 
     /**
      * Constructor
diff --git a/src/SourceMap/SourceMapGenerator.php b/src/SourceMap/SourceMapGenerator.php
index 6e969cae..3f446aa4 100644
--- a/src/SourceMap/SourceMapGenerator.php
+++ b/src/SourceMap/SourceMapGenerator.php
@@ -33,7 +33,7 @@ class SourceMapGenerator
      *
      * @var array
      */
-    protected $defaultOptions = array(
+    protected $defaultOptions = [
         // an optional source root, useful for relocating source files
         // on a server or removing repeated values in the 'sources' entry.
         // This value is prepended to the individual entries in the 'source' field.
@@ -56,7 +56,7 @@ class SourceMapGenerator
 
         // base path for filename normalization
         'sourceMapBasepath' => ''
-    );
+    ];
 
     /**
      * The base64 VLQ encoder
@@ -70,22 +70,22 @@ class SourceMapGenerator
      *
      * @var array
      */
-    protected $mappings = array();
+    protected $mappings = [];
 
     /**
      * Array of contents map
      *
      * @var array
      */
-    protected $contentsMap = array();
+    protected $contentsMap = [];
 
     /**
      * File to content map
      *
      * @var array
      */
-    protected $sources = array();
-    protected $source_keys = array();
+    protected $sources = [];
+    protected $source_keys = [];
 
     /**
      * @var array
@@ -109,13 +109,13 @@ public function __construct(array $options = [])
      */
     public function addMapping($generatedLine, $generatedColumn, $originalLine, $originalColumn, $sourceFile)
     {
-        $this->mappings[] = array(
+        $this->mappings[] = [
             'generated_line' => $generatedLine,
             'generated_column' => $generatedColumn,
             'original_line' => $originalLine,
             'original_column' => $originalColumn,
             'source_file' => $sourceFile
-        );
+        ];
 
         $this->sources[$sourceFile] = $sourceFile;
     }
@@ -156,7 +156,7 @@ public function saveMap($content)
      */
     public function generateJson()
     {
-        $sourceMap = array();
+        $sourceMap = [];
         $mappings  = $this->generateMappings();
 
         // File version (always the first entry in the object) and must be a positive integer.
@@ -178,14 +178,14 @@ public function generateJson()
         }
 
         // A list of original sources used by the 'mappings' entry.
-        $sourceMap['sources'] = array();
+        $sourceMap['sources'] = [];
 
         foreach ($this->sources as $source_uri => $source_filename) {
             $sourceMap['sources'][] = $this->normalizeFilename($source_filename);
         }
 
         // A list of symbol names used by the 'mappings' entry.
-        $sourceMap['names'] = array();
+        $sourceMap['names'] = [];
 
         // A string with the encoded mapping data.
         $sourceMap['mappings'] = $mappings;
@@ -216,7 +216,7 @@ protected function getSourcesContent()
             return null;
         }
 
-        $content = array();
+        $content = [];
 
         foreach ($this->sources as $sourceFile) {
             $content[] = file_get_contents($sourceFile);
@@ -239,7 +239,7 @@ public function generateMappings()
         $this->source_keys = array_flip(array_keys($this->sources));
 
         // group mappings by generated line number.
-        $groupedMap = $groupedMapEncoded = array();
+        $groupedMap = $groupedMapEncoded = [];
 
         foreach ($this->mappings as $m) {
             $groupedMap[$m['generated_line']][] = $m;
@@ -253,7 +253,7 @@ public function generateMappings()
                 $groupedMapEncoded[] = ';';
             }
 
-            $lineMapEncoded = array();
+            $lineMapEncoded = [];
             $lastGeneratedColumn = 0;
 
             foreach ($line_map as $m) {
diff --git a/src/Util.php b/src/Util.php
index 7526e020..a1e50658 100644
--- a/src/Util.php
+++ b/src/Util.php
@@ -63,7 +63,7 @@ public static function checkRange($name, Range $range, $value, $unit = '')
      */
     public static function encodeURIComponent($string)
     {
-        $revert = array('%21' => '!', '%2A' => '*', '%27' => "'", '%28' => '(', '%29' => ')');
+        $revert = ['%21' => '!', '%2A' => '*', '%27' => "'", '%28' => '(', '%29' => ')'];
 
         return strtr(rawurlencode($string), $revert);
     }