diff --git a/lib/hls/hls_classes.js b/lib/hls/hls_classes.js
index 3a6f74a773..b95064c296 100644
--- a/lib/hls/hls_classes.js
+++ b/lib/hls/hls_classes.js
@@ -233,6 +233,10 @@ shaka.hls.Segment = class {
    */
   get absoluteUri() {
     if (!this.absoluteUri_) {
+      goog.asserts.assert(this.absoluteMediaPlaylistUri_,
+          'An absolute Media Playlist URI should be defined!');
+      goog.asserts.assert(this.verbatimSegmentUri_,
+          'An verbatim segment URI should be defined!');
       this.absoluteUri_ = shaka.hls.Utils.constructAbsoluteUri(
           this.absoluteMediaPlaylistUri_, this.verbatimSegmentUri_);
       this.absoluteMediaPlaylistUri_ = null;