diff --git a/lib/media/presentation_timeline.js b/lib/media/presentation_timeline.js
index 2e5309bfd6..4aff0f0bfe 100644
--- a/lib/media/presentation_timeline.js
+++ b/lib/media/presentation_timeline.js
@@ -98,7 +98,7 @@ shaka.media.PresentationTimeline = class {
     this.startTimeLocked_ = false;
 
     /** @private {?number} */
-    this.initialProgramDateTime_ = null;
+    this.initialProgramDateTime_ = presentationStartTime;
   }