--- a/dom/media/test/mochitest.ini
+++ b/dom/media/test/mochitest.ini
@@ -689,16 +689,17 @@ skip-if = (toolkit == 'gonk') # B2G emul
 tags=msg
 [test_mediarecorder_creation.html]
 tags=msg capturestream
 [test_mediarecorder_creation_fail.html]
 tags=msg
 [test_mediarecorder_getencodeddata.html]
 tags=msg
 [test_mediarecorder_principals.html]
+skip-if = (os == 'linux' && bits == 64) # See bug 1266345
 tags=msg
 [test_mediarecorder_record_4ch_audiocontext.html]
 tags=msg
 [test_mediarecorder_record_audiocontext.html]
 tags=msg
 [test_mediarecorder_record_audiocontext_mlk.html]
 tags=msg
 [test_mediarecorder_record_audionode.html]