diff --git a/simpleshop-cz.php b/simpleshop-cz.php
index 4a8c95a..ca27bad 100644
--- a/simpleshop-cz.php
+++ b/simpleshop-cz.php
@@ -21,12 +21,11 @@
 
 require_once __DIR__ . '/vendor/autoload.php';
 
-define( 'SIMPLESHOP_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
-define( 'SIMPLESHOP_PLUGIN_URL', plugin_dir_url( __FILE__ ) );
 define( 'SIMPLESHOP_PLUGIN_VERSION', 'dev-master' );
 define( 'SIMPLESHOP_PREFIX', '_ssc_' );
 
 /**
  * Start plugin
  */
+SimpleShop::$pluginMainFile = __FILE__;
 SimpleShop::getInstance();
diff --git a/src/Admin.php b/src/Admin.php
index d1ce6d5..4cd6028 100644
--- a/src/Admin.php
+++ b/src/Admin.php
@@ -16,10 +16,20 @@ class Admin {
 	 * @var Plugin
 	 */
 	private $loader;
+	/**
+	 * @var string
+	 */
+	private $pluginDirUrl;
 
+	/**
+	 * @param Plugin $loader
+	 * @param string $pluginMainFile
+	 */
 	public function __construct(Plugin $loader) {
 		$this->loader = $loader;
 
+		$this->pluginDirUrl = plugin_dir_url($loader->get_plugin_main_file());
+
 		add_action( 'admin_menu', [ $this, 'add_settings_page' ] );
 		add_filter( 'manage_edit-ssc_group_columns', [ $this, 'ssc_group_columns' ] );
 		add_action( 'manage_ssc_group_posts_custom_column', [ $this, 'ssc_group_column_content' ], 10, 2 );
@@ -122,7 +132,7 @@ public function tiny_mce_new_buttons() {
 	 * @return mixed
 	 */
 	public function tiny_mce_add_buttons( $plugins ) {
-		$plugins['ssctinymceplugin'] = SIMPLESHOP_PLUGIN_URL . 'js/tiny-mce/tiny-mce.js';
+		$plugins['ssctinymceplugin'] = $this->pluginDirUrl . 'js/tiny-mce/tiny-mce.js';
 
 		return $plugins;
 	}
@@ -192,7 +202,7 @@ public function add_settings_page() {
             'manage_options',
             'simple_shop_settings',
 			[ $this, 'render_settings_page' ],
-            SIMPLESHOP_PLUGIN_URL . '/img/white_logo.png',
+			$this->pluginDirUrl . '/img/white_logo.png',
             99
 		);
 	}
@@ -230,7 +240,7 @@ public function ssc_group_column_content( $column, $post_id ) {
 	 * Enqueue admin scripts
 	 */
 	public function enqueue_admin_scripts() {
-		wp_enqueue_style( 'ssc', SIMPLESHOP_PLUGIN_URL . 'css/ssc.css' );
+		wp_enqueue_style( 'ssc', $this->pluginDirUrl . 'css/ssc.css' );
 		wp_register_style( 'jquery-ui', 'https://code.jquery.com/ui/1.11.2/themes/smoothness/jquery-ui.css' );
 		wp_enqueue_style( 'jquery-ui' );
 	}
diff --git a/src/Plugin.php b/src/Plugin.php
index 3658773..a9e33b9 100644
--- a/src/Plugin.php
+++ b/src/Plugin.php
@@ -28,7 +28,17 @@ class Plugin {
 	 */
 	private $access;
 
-	public function __construct() {
+	/**
+	 * @var string
+	 */
+	private $pluginMainFile;
+
+	/**
+	 * @param string $mainFile Filename of main plugin path. Used for native WP functions
+	 */
+	public function __construct( $mainFile ) {
+		$this->pluginMainFile = $mainFile;
+
 		$this->init();
 		$this->init_i18n();
 
@@ -36,7 +46,7 @@ public function __construct() {
 		$this->email      = $this->load_email();
 
 		add_action( 'tgmpa_register', [ $this, 'register_required_plugins' ] );
-		register_activation_hook( __FILE__, [ $this, 'ssc_activation_hook' ] );
+		register_activation_hook( plugin_dir_path( $this->pluginMainFile ), [ $this, 'ssc_activation_hook' ] );
 	}
 
 	private function init() {
@@ -150,7 +160,11 @@ public function init_i18n() {
 	}
 
 	public function load_textdomain_i18n() {
-		$plugin_rel_path = str_replace( WP_PLUGIN_DIR . '/', '', SIMPLESHOP_PLUGIN_DIR . 'languages/' );
+		$plugin_rel_path = str_replace( WP_PLUGIN_DIR . '/', '', plugin_dir_path( $this->pluginMainFile ) . 'languages/' );
 		load_plugin_textdomain( 'simpleshop-cz', false, $plugin_rel_path );
 	}
+
+	public function get_plugin_main_file() {
+		return $this->pluginMainFile;
+	}
 }
diff --git a/src/SimpleShop.php b/src/SimpleShop.php
index 19e74b7..c39242d 100644
--- a/src/SimpleShop.php
+++ b/src/SimpleShop.php
@@ -9,6 +9,11 @@
 namespace Redbit\SimpleShop\WpPlugin;
 
 class SimpleShop {
+	/**
+	 * @var string
+	 */
+	public static $pluginMainFile = __DIR__ . '/../simpleshop-cz.php';
+
 	/**
 	 * @var Plugin|null
 	 */
@@ -29,6 +34,6 @@ public static function getInstance() {
 	 * @return Plugin
 	 */
 	protected static function factory() {
-		return new Plugin();
+		return new Plugin(self::$pluginMainFile);
 	}
 }