--- a/testing/mozharness/scripts/android_emulator_unittest.py
+++ b/testing/mozharness/scripts/android_emulator_unittest.py
@@ -165,26 +165,26 @@ class AndroidEmulatorTest(BlobUploadMixi
             if key not in abs_dirs:
                 abs_dirs[key] = dirs[key]
         self.abs_dirs = abs_dirs
         return self.abs_dirs
 
     @PreScriptAction('create-virtualenv')
     def _pre_create_virtualenv(self, action):
         dirs = self.query_abs_dirs()
-
+        requirements = None
         if os.path.isdir(dirs['abs_mochitest_dir']):
             # mochitest is the only thing that needs this
             requirements = os.path.join(dirs['abs_mochitest_dir'],
                         'websocketprocessbridge',
                         'websocketprocessbridge_requirements.txt')
         elif self.test_suite == 'marionette':
             requirements = os.path.join(dirs['abs_test_install_dir'],
                                     'config', 'marionette_requirements.txt')
-
+        if requirements:
             self.register_virtualenv_module(requirements=[requirements],
                                             two_pass=True)
 
     def _launch_emulator(self):
         env = self.query_env()
 
         # Set $LD_LIBRARY_PATH to self.dirs['abs_work_dir'] so that
         # the emulator picks up the symlink to libGL.so.1 that we