diff --git a/lib/media/streaming_engine.js b/lib/media/streaming_engine.js
index 5625138d59..6cdd405b32 100644
--- a/lib/media/streaming_engine.js
+++ b/lib/media/streaming_engine.js
@@ -1672,7 +1672,7 @@ shaka.media.StreamingEngine = class {
     // See DASH sec. 5.10.3.3.1
     // If a DASH client detects an event message box with a scheme that is not
     // defined in MPD, the client is expected to ignore it.
-    if (emsgSchemeIdUris.includes(schemeId) ||
+    if ((emsgSchemeIdUris && emsgSchemeIdUris.includes(schemeId)) ||
         this.config_.dispatchAllEmsgBoxes) {
       // See DASH sec. 5.10.4.1
       // A special scheme in DASH used to signal manifest updates.