1 files changed, 1 insertions, 1 deletions

diff --git a/beamer/viewer/screen/timer.js b/beamer/viewer/screen/timer.js
index 112a421..0f5d9bc 100644
--- a/beamer/viewer/screen/timer.js
+++ b/beamer/viewer/screen/timer.js
@@ -78,7 +78,7 @@ class Timer {
   _setDisplay(seconds) {
     const dateObj = new Date(null);
     dateObj.setSeconds(seconds);
-    this.display.textContent = dateObj.toISOString().substr(11, 8);
+    this.display.textContent = dateObj.toISOString().slice(11, 11+8);
   }
 
   _toggleDisplay(active) {