--- a/build/mobile/remoteautomation.py
+++ b/build/mobile/remoteautomation.py
@@ -8,16 +8,20 @@ import os
 import automationutils
 import tempfile
 import shutil
 import subprocess
 
 from automation import Automation
 from devicemanager import NetworkTools, DMError
 
+# signatures for logcat messages that we don't care about much
+fennecLogcatFilters = [ "The character encoding of the HTML document was not declared",
+                           "Use of Mutation Events is deprecated. Use MutationObserver instead." ]
+
 class RemoteAutomation(Automation):
     _devicemanager = None
 
     def __init__(self, deviceManager, appName = '', remoteLog = None):
         self._devicemanager = deviceManager
         self._appName = appName
         self._remoteProfile = None
         self._remoteLog = remoteLog

--- a/layout/tools/reftest/remotereftest.py
+++ b/layout/tools/reftest/remotereftest.py
@@ -10,17 +10,17 @@ import traceback
 
 # We need to know our current directory so that we can serve our test files from it.
 SCRIPT_DIRECTORY = os.path.abspath(os.path.realpath(os.path.dirname(sys.argv[0])))
 
 from runreftest import RefTest
 from runreftest import ReftestOptions
 from automation import Automation
 import devicemanager, devicemanagerADB, devicemanagerSUT
-from remoteautomation import RemoteAutomation
+from remoteautomation import RemoteAutomation, fennecLogcatFilters
 
 class RemoteOptions(ReftestOptions):
     def __init__(self, automation):
         ReftestOptions.__init__(self, automation)
 
         defaults = {}
         defaults["logFile"] = "reftest.log"
         # app, xrePath and utilityPath variables are set in main function
@@ -445,18 +445,18 @@ def main(args):
         reftest.runTests(manifest, options, cmdlineArgs)
     except:
         print "Automation Error: Exception caught while running tests"
         traceback.print_exc()
         retVal = 1
 
     reftest.stopWebServer(options)
     try:
-        logcat = dm.getLogcat()
-        print ''.join(logcat[-500:-1])
+        logcat = dm.getLogcat(filterOutRegexps=fennecLogcatFilters)
+        print ''.join(logcat)
         print dm.getInfo()
     except devicemanager.DMError:
         print "WARNING: Error getting device information at end of test"
 
     return retVal
 
 if __name__ == "__main__":
     sys.exit(main(sys.argv[1:]))

--- a/testing/mochitest/runtestsremote.py
+++ b/testing/mochitest/runtestsremote.py
@@ -7,17 +7,17 @@ import os
 import time
 import tempfile
 import re
 import traceback
 
 sys.path.insert(0, os.path.abspath(os.path.realpath(os.path.dirname(sys.argv[0]))))
 
 from automation import Automation
-from remoteautomation import RemoteAutomation
+from remoteautomation import RemoteAutomation, fennecLogcatFilters
 from runtests import Mochitest
 from runtests import MochitestOptions
 from runtests import MochitestServer
 
 import devicemanager, devicemanagerADB, devicemanagerSUT
 import manifestparser
 
 class RemoteOptions(MochitestOptions):
@@ -530,18 +530,18 @@ def main():
             try:
                 mochitest.cleanup(None, options)
             except devicemanager.DMError:
                 # device error cleaning up... oh well!
                 pass
             retVal = 1
 
     try:
-        logcat = dm.getLogcat()
-        print ''.join(logcat[-500:-1])
+        logcat = dm.getLogcat(filterOutRegexps=fennecLogcatFilters)
+        print ''.join(logcat)
         print dm.getInfo()
     except devicemanager.DMError:
         print "WARNING: Error getting device information at end of test"
 
     sys.exit(retVal)
         
 if __name__ == "__main__":
     main()