diff --git a/framework/caching/Cache.php b/framework/caching/Cache.php
index 70cf8cba2a..fb56d5e066 100644
--- a/framework/caching/Cache.php
+++ b/framework/caching/Cache.php
@@ -70,6 +70,18 @@ abstract class Cache extends Component implements \ArrayAccess
 	public $serializer;
 
 
+	/**
+	 * Initializes the application component.
+	 * This method overrides the parent implementation by setting default cache key prefix.
+	 */
+	public function init()
+	{
+		parent::init();
+		if ($this->keyPrefix === null) {
+			$this->keyPrefix = \Yii::$app->id;
+		}
+	}
+
 	/**
 	 * Builds a normalized cache key from a given key.
 	 *