diff --git a/core/AssetManager/UIAssetMerger/StylesheetUIAssetMerger.php b/core/AssetManager/UIAssetMerger/StylesheetUIAssetMerger.php
index de0f5f1ffa7720bd96181c2dc41c31fce6548b97..232b1ab8258f5e33b3eff08f2be4d349bc640cbf 100644
--- a/core/AssetManager/UIAssetMerger/StylesheetUIAssetMerger.php
+++ b/core/AssetManager/UIAssetMerger/StylesheetUIAssetMerger.php
@@ -92,7 +92,7 @@ class StylesheetUIAssetMerger extends UIAssetMerger
      * Rewrite CSS url() directives
      *
      * @param string $content
-     * @param function $pathsRewriter
+     * @param callable $pathsRewriter
      * @return string
      */
     private function rewriteCssImagePaths($content, $pathsRewriter)
@@ -105,7 +105,7 @@ class StylesheetUIAssetMerger extends UIAssetMerger
      * Rewrite CSS import directives
      *
      * @param string $content
-     * @param function $pathsRewriter
+     * @param callable $pathsRewriter
      * @return string
      */
     private function rewriteCssImportPaths($content, $pathsRewriter)
@@ -119,7 +119,7 @@ class StylesheetUIAssetMerger extends UIAssetMerger
      * - rewrites paths defined relatively to their css/less definition file
      * - rewrite windows directory separator \\ to /
      *
-     * @param string $baseDirectory
+     * @param UIAsset $uiAsset
      * @return \Closure
      */
     private function getCssPathsRewriter($uiAsset)
diff --git a/core/CliMulti/CliPhp.php b/core/CliMulti/CliPhp.php
index 3bf7b3888e839eb76962548244ab94fee157bbee..101f9277c6caa07cde4528f632e07ea70b5c52d3 100644
--- a/core/CliMulti/CliPhp.php
+++ b/core/CliMulti/CliPhp.php
@@ -87,10 +87,11 @@ class CliPhp
                 return $path;
             }
         }
+        return null;
     }
 
     /**
-     * @param $bin PHP binary
+     * @param string $bin PHP binary
      * @return string
      */
     private function getPhpVersion($bin)
diff --git a/core/Common.php b/core/Common.php
index 14007045996dfa7a454584982ca8ce8d74a02465..22f8cac2f137514c5c327d920d1d295c1c1b837d 100644
--- a/core/Common.php
+++ b/core/Common.php
@@ -111,12 +111,12 @@ class Common
      */
     public static function isGoalPluginEnabled()
     {
-        return \Piwik\Plugin\Manager::getInstance()->isPluginActivated('Goals');
+        return Plugin\Manager::getInstance()->isPluginActivated('Goals');
     }
 
     public static function isActionsPluginEnabled()
     {
-        return \Piwik\Plugin\Manager::getInstance()->isPluginActivated('Actions');
+        return Plugin\Manager::getInstance()->isPluginActivated('Actions');
     }
 
     /**
@@ -535,7 +535,7 @@ class Common
     }
 
     /**
-     * Configureable hash() algorithm (defaults to md5)
+     * Configurable hash() algorithm (defaults to md5)
      *
      * @param string $str String to be hashed
      * @param bool $raw_output
@@ -717,14 +717,14 @@ class Common
     /**
      * Returns the list of parent classes for the given class.
      *
-     * @param  string    $klass   A class name.
+     * @param  string    $class   A class name.
      * @return string[]  The list of parent classes in order from highest ancestor to the descended class.
      */
-    public static function getClassLineage($klass)
+    public static function getClassLineage($class)
     {
-        $klasses = array_merge(array($klass), array_values(class_parents($klass, $autoload = false)));
+        $classes = array_merge(array($class), array_values(class_parents($class, $autoload = false)));
 
-        return array_reverse($klasses);
+        return array_reverse($classes);
     }
 
     /*
@@ -1081,7 +1081,7 @@ class Common
     /**
      * Returns the continent of a given country
      *
-     * @param string $country 2 letters isocode
+     * @param string $country 2 letters iso code
      *
      * @return string  Continent (3 letters code : afr, asi, eur, amn, ams, oce)
      */
@@ -1245,7 +1245,7 @@ class Common
      * Marks an orphaned object for garbage collection.
      *
      * For more information: {@link https://github.com/piwik/piwik/issues/374}
-     * @param $var The object to destroy.
+     * @param mixed $var The object to destroy.
      * @api
      */
     public static function destroy(&$var)
diff --git a/core/DataTable.php b/core/DataTable.php
index d67e0984cb012a94b3e0d509cffd7c9abc24e08e..884100b53a64316a7d8bafec402ac50c68d72b60 100644
--- a/core/DataTable.php
+++ b/core/DataTable.php
@@ -895,7 +895,7 @@ class DataTable implements DataTableInterface, \IteratorAggregate, \ArrayAccess
     /**
      * Returns an array containing all column values of columns whose name starts with `$name`.
      *
-     * @param $namePrefix The column name prefix.
+     * @param string $namePrefix The column name prefix.
      * @return array The array of column values.
      */
     public function getColumnsStartingWith($namePrefix)
diff --git a/core/DataTable/Map.php b/core/DataTable/Map.php
index ccf201c5be90bec1b6292c00a7c904ad36510326..8f9d259f104e512397a9789f8901f7b9899cc7bf 100644
--- a/core/DataTable/Map.php
+++ b/core/DataTable/Map.php
@@ -8,6 +8,7 @@
  */
 namespace Piwik\DataTable;
 
+use Closure;
 use Piwik\Common;
 use Piwik\DataTable;
 use Piwik\DataTable\Renderer\Console;
@@ -199,6 +200,8 @@ class Map implements DataTableInterface
                 return $subTableRow;
             }
         }
+
+        return null;
     }
 
     /**
diff --git a/core/DataTable/Row.php b/core/DataTable/Row.php
index a6c1de7c16a5d51aa02fd57fedb9d8d413bca499..4b5547cf8b4789632f82f7ba88e431e8532ecc74 100644
--- a/core/DataTable/Row.php
+++ b/core/DataTable/Row.php
@@ -326,7 +326,7 @@ class Row implements \ArrayAccess, \IteratorAggregate
     /**
      * Set all the columns at once. Overwrites **all** previously set columns.
      *
-     * @param array eg, `array('label' => 'www.php.net', 'nb_visits' => 15894)`
+     * @param array $columns eg, `array('label' => 'www.php.net', 'nb_visits' => 15894)`
      */
     public function setColumns($columns)
     {
diff --git a/core/Notification/Manager.php b/core/Notification/Manager.php
index 402f1aeaf0a2a5c8f8da8544a8676a5f62225476..666042977986152855a24520d1b6530e74abf68b 100644
--- a/core/Notification/Manager.php
+++ b/core/Notification/Manager.php
@@ -43,7 +43,7 @@ class Manager
     /**
      * Removes a posted notification by ID.
      *
-     * @param $id The notification ID, see {@link notify()}.
+     * @param string $id The notification ID, see {@link notify()}.
      */
     public static function cancel($id)
     {
diff --git a/core/View.php b/core/View.php
index 423aaeb278e5fe366f42240d67de6200309bc381..08c65695b91860d89f1557cfe0b4b6deb0670597 100644
--- a/core/View.php
+++ b/core/View.php
@@ -192,7 +192,7 @@ class View implements ViewInterface
     /**
      * Returns true if a template variable has been set or not.
      *
-     * @param $name The name of the template variable.
+     * @param string $name The name of the template variable.
      * @return bool
      */
     public function __isset($name)