diff --git a/mach b/mach
index 94fcdde689a0..e39da5d95e21 100755
--- a/mach
+++ b/mach
@@ -24,7 +24,6 @@ py2commands="
     geckodriver-test
     geckoview-junit
     gradle
-    gtest
     hazards
     jsapi-tests
     jsshell-bench
diff --git a/python/mach/mach/mixin/process.py b/python/mach/mach/mixin/process.py
index 2e3fa3a857fb..32d2760071b1 100644
--- a/python/mach/mach/mixin/process.py
+++ b/python/mach/mach/mixin/process.py
@@ -112,7 +112,7 @@ class ProcessExecutionMixin(LoggingMixin):
         if python_unbuffered:
             use_env['PYTHONUNBUFFERED'] = '1'
 
-        self.log(logging.DEBUG, 'process', {'env': use_env}, 'Environment: {env}')
+        self.log(logging.DEBUG, 'process', {'env': str(use_env)}, 'Environment: {env}')
 
         use_env = ensure_subprocess_env(use_env)
         if pass_thru:
diff --git a/testing/gtest/remotegtests.py b/testing/gtest/remotegtests.py
index a24ac5fbd499..04bfeca073c2 100644
--- a/testing/gtest/remotegtests.py
+++ b/testing/gtest/remotegtests.py
@@ -12,6 +12,7 @@ import glob
 import os
 import posixpath
 import shutil
+import six
 import sys
 import tempfile
 import time
@@ -102,6 +103,8 @@ class RemoteGTests(object):
             if not os.path.isdir(f):
                 self.device.push(f, self.remote_profile)
 
+        if test_filter is not None:
+            test_filter = six.ensure_text(test_filter)
         env = self.build_environment(shuffle, test_filter, enable_webrender)
         args = ["-unittest", "--gtest_death_test_style=threadsafe",
                 "-profile %s" % self.remote_profile]
@@ -301,6 +304,7 @@ class AppWaiter(object):
             return False
         if not new_content:
             return False
+        new_content = six.ensure_text(new_content)
         last_full_line_pos = new_content.rfind('\n')
         if last_full_line_pos <= 0:
             # wait for a full line