diff --git a/assets/reader/js/index.js b/assets/reader/js/index.js
index 75c2e506..3cd62d3c 100644
--- a/assets/reader/js/index.js
+++ b/assets/reader/js/index.js
@@ -423,6 +423,7 @@ const TTSController = () => {
       return;
     }
     stopEvent(e);
+    controllerElement ??= document.getElementById('TTS-Controller');
     const touch = e.changedTouches[0];
     const bounds = controllerElement.getBoundingClientRect();
     dragOffsetX = touch.clientX - bounds.left;