diff --git a/src/Task/AbstractTask.php b/src/Task/AbstractTask.php
index 0ee7c2f..395dd5f 100644
--- a/src/Task/AbstractTask.php
+++ b/src/Task/AbstractTask.php
@@ -61,7 +61,8 @@ abstract class AbstractTask
         if (!is_array($options)) {
             $options = [];
         }
-        $this->options = $options;
+
+        $this->options = array_merge($options, $this->getDefaults());
         return $this;
     }
 
@@ -76,4 +77,13 @@ abstract class AbstractTask
         $this->runtime = $runtime;
         return $this;
     }
+
+    /**
+     * Return Default options
+     * @return array
+     */
+    public function getDefaults()
+    {
+        return [];
+    }
 }
diff --git a/src/Task/BuiltIn/FS/AbstractFileTask.php b/src/Task/BuiltIn/FS/AbstractFileTask.php
index c2e4685..eb782b2 100644
--- a/src/Task/BuiltIn/FS/AbstractFileTask.php
+++ b/src/Task/BuiltIn/FS/AbstractFileTask.php
@@ -29,8 +29,10 @@ abstract class AbstractFileTask extends AbstractTask
     protected function getOptions()
     {
         $mandatory = $this->getParameters();
+        $defaults = array_keys($this->getDefaults());
+        $missing = array_diff($mandatory, $defaults);
 
-        foreach ($mandatory as $parameter) {
+        foreach ($missing as $parameter) {
             if (!array_key_exists($parameter, $this->options)) {
                 throw new ErrorException(sprintf('Parameter "%s" is not defined', $parameter));
             }
diff --git a/src/Task/BuiltIn/FS/ChangeModeTask.php b/src/Task/BuiltIn/FS/ChangeModeTask.php
index 883fce5..3ad05ba 100644
--- a/src/Task/BuiltIn/FS/ChangeModeTask.php
+++ b/src/Task/BuiltIn/FS/ChangeModeTask.php
@@ -50,4 +50,9 @@ class ChangeModeTask extends AbstractFileTask
     {
         return ['file', 'mode', 'flags'];
     }
+
+    public function getDefaults()
+    {
+        return ['flags' => null];
+    }
 }