--- a/xpcom/base/ErrorList.h
+++ b/xpcom/base/ErrorList.h
@@ -983,16 +983,19 @@
   ERROR(NS_ERROR_DOM_MEDIA_METADATA_ERR,        FAILURE(6)),
   ERROR(NS_ERROR_DOM_MEDIA_OVERFLOW_ERR,        FAILURE(7)),
   ERROR(NS_ERROR_DOM_MEDIA_END_OF_STREAM,       FAILURE(8)),
   ERROR(NS_ERROR_DOM_MEDIA_WAITING_FOR_DATA,    FAILURE(9)),
   ERROR(NS_ERROR_DOM_MEDIA_CANCELED,            FAILURE(10)),
   ERROR(NS_ERROR_DOM_MEDIA_MEDIASINK_ERR,       FAILURE(11)),
   ERROR(NS_ERROR_DOM_MEDIA_DEMUXER_ERR,         FAILURE(12)),
   ERROR(NS_ERROR_DOM_MEDIA_CDM_ERR,             FAILURE(13)),
+
+  /* Internal platform-related errors */
+  ERROR(NS_ERROR_DOM_MEDIA_CUBEB_INITIALIZATION_ERR,  FAILURE(101)),
 #undef MODULE
 
   /* ======================================================================= */
   /* 51: NS_ERROR_MODULE_GENERAL */
   /* ======================================================================= */
 #define MODULE NS_ERROR_MODULE_GENERAL
   /* Error code used internally by the incremental downloader to cancel the
    * network channel when the download is already complete. */