diff --git a/src/App.php b/src/App.php
index 8f512894c3..f4fb3fa3d9 100644
--- a/src/App.php
+++ b/src/App.php
@@ -182,8 +182,8 @@ class App
 	 */
 	public function registerStylesheet($path)
 	{
-		if (mb_strpos($path, $this->getBasePath() . DIRECTORY_SEPARATOR) == 0) {
-				$path = mb_substr($path, mb_strlen($this->getBasePath() . DIRECTORY_SEPARATOR));
+		if (mb_strpos($path, $this->getBasePath() . DIRECTORY_SEPARATOR) === 0) {
+			$path = mb_substr($path, mb_strlen($this->getBasePath() . DIRECTORY_SEPARATOR));
 		}
 
 		$this->stylesheets[] = trim($path, '/');