diff --git a/testing/marionette/client/marionette/geckoinstance.py b/testing/marionette/client/marionette/geckoinstance.py
index 96ccdff30da..9eea4ef3db6 100644
--- a/testing/marionette/client/marionette/geckoinstance.py
+++ b/testing/marionette/client/marionette/geckoinstance.py
@@ -63,14 +63,10 @@ class GeckoInstance(object):
             env=env,
             symbols_path=self.symbols_path,
             process_args={
-                'processOutputLine': [on_output],
+                'processOutputLine': [NullOutput()],
                 'logfile': self.gecko_log})
         self.runner.start()
 
-    def on_output(self, line):
-        if line.startswith('TEST-START'):
-            self.runner.last_test = line.split()[-1]
-
     def check_for_crashes(self):
         return self.runner.check_for_crashes()
 
@@ -84,5 +80,10 @@ class B2GDesktopInstance(GeckoInstance):
     required_prefs = {"focusmanager.testmode": True}
 
 
+class NullOutput(object):
+    def __call__(self, line):
+        pass
+
+
 apps = {'b2g': B2GDesktopInstance,
         'b2gdesktop': B2GDesktopInstance}
diff --git a/testing/mozbase/mozrunner/mozrunner/base/runner.py b/testing/mozbase/mozrunner/mozrunner/base/runner.py
index 7caf64189f9..a0142d1053d 100644
--- a/testing/mozbase/mozrunner/mozrunner/base/runner.py
+++ b/testing/mozbase/mozrunner/mozrunner/base/runner.py
@@ -177,7 +177,6 @@ class BaseRunner(object):
         if not dump_directory:
             dump_directory = os.path.join(self.profile.profile, 'minidumps')
 
-        test_name = test_name or self.last_test
         crashed = False
         try:
             crashed = mozcrash.check_for_crashes(dump_directory,