diff --git a/testing/mochitest/moz.build b/testing/mochitest/moz.build
index 65fb26541236..fcb0ca9f35fb 100644
--- a/testing/mochitest/moz.build
+++ b/testing/mochitest/moz.build
@@ -160,5 +160,6 @@ TEST_HARNESS_FILES.testing.mochitest.iceserver += [
 
 TEST_HARNESS_FILES.testing.mochitest.websocketprocessbridge += [
     '/testing/tools/websocketprocessbridge/websocketprocessbridge.py',
+    '/testing/tools/websocketprocessbridge/websocketprocessbridge_requirements.txt',
 ]
 
diff --git a/testing/mozharness/scripts/android_emulator_unittest.py b/testing/mozharness/scripts/android_emulator_unittest.py
index 356e75ebf9ee..a0b8671550cf 100644
--- a/testing/mozharness/scripts/android_emulator_unittest.py
+++ b/testing/mozharness/scripts/android_emulator_unittest.py
@@ -22,7 +22,7 @@ sys.path.insert(1, os.path.dirname(sys.path[0]))
 from mozprocess import ProcessHandler
 
 from mozharness.base.log import FATAL
-from mozharness.base.script import BaseScript
+from mozharness.base.script import BaseScript, PreScriptAction
 from mozharness.base.vcs.vcsbase import VCSMixin
 from mozharness.mozilla.blob_upload import BlobUploadMixin, blobupload_config_options
 from mozharness.mozilla.mozbase import MozbaseMixin
@@ -136,6 +136,8 @@ class AndroidEmulatorTest(BlobUploadMixin, TestingMixin, EmulatorMixin, VCSMixin
             abs_dirs['abs_work_dir'], 'blobber_upload_dir')
         dirs['abs_emulator_dir'] = os.path.join(
             abs_dirs['abs_work_dir'], 'emulator')
+        dirs['abs_mochitest_dir'] = os.path.join(
+            dirs['abs_test_install_dir'], 'mochitest')
 
         if self.config.get("developer_mode"):
             dirs['abs_avds_dir'] = os.path.join(
@@ -149,6 +151,19 @@ class AndroidEmulatorTest(BlobUploadMixin, TestingMixin, EmulatorMixin, VCSMixin
         self.abs_dirs = abs_dirs
         return self.abs_dirs
 
+    @PreScriptAction('create-virtualenv')
+    def _pre_create_virtualenv(self, action):
+        dirs = self.query_abs_dirs()
+
+        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')
+
+            self.register_virtualenv_module(requirements=[requirements],
+                                            two_pass=True)
+
     def _launch_emulator(self):
         env = self.query_env()
 
diff --git a/testing/mozharness/scripts/androidx86_emulator_unittest.py b/testing/mozharness/scripts/androidx86_emulator_unittest.py
index 41fbd26d97b7..1d1c96df9d99 100644
--- a/testing/mozharness/scripts/androidx86_emulator_unittest.py
+++ b/testing/mozharness/scripts/androidx86_emulator_unittest.py
@@ -21,7 +21,7 @@ sys.path.insert(1, os.path.dirname(sys.path[0]))
 from mozprocess import ProcessHandler
 
 from mozharness.base.log import FATAL
-from mozharness.base.script import BaseScript, PostScriptRun
+from mozharness.base.script import BaseScript, PostScriptRun, PreScriptAction
 from mozharness.base.vcs.vcsbase import VCSMixin
 from mozharness.mozilla.blob_upload import BlobUploadMixin, blobupload_config_options
 from mozharness.mozilla.mozbase import MozbaseMixin
@@ -143,6 +143,8 @@ class AndroidEmulatorTest(BlobUploadMixin, TestingMixin, EmulatorMixin, VCSMixin
             abs_dirs['abs_work_dir'], 'blobber_upload_dir')
         dirs['abs_emulator_dir'] = os.path.join(
             abs_dirs['abs_work_dir'], 'emulator')
+        dirs['abs_mochitest_dir'] = os.path.join(
+            dirs['abs_test_install_dir'], 'mochitest')
 
         if self.config.get("developer_mode"):
             dirs['abs_avds_dir'] = os.path.join(
@@ -156,6 +158,19 @@ class AndroidEmulatorTest(BlobUploadMixin, TestingMixin, EmulatorMixin, VCSMixin
         self.abs_dirs = abs_dirs
         return self.abs_dirs
 
+    @PreScriptAction('create-virtualenv')
+    def _pre_create_virtualenv(self, action):
+        dirs = self.query_abs_dirs()
+
+        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')
+
+            self.register_virtualenv_module(requirements=[requirements],
+                                            two_pass=True)
+
     def _build_arg(self, option, value):
         """
         Build a command line argument
diff --git a/testing/mozharness/scripts/desktop_unittest.py b/testing/mozharness/scripts/desktop_unittest.py
index d8eb1c7c1ce8..d28d335343d5 100755
--- a/testing/mozharness/scripts/desktop_unittest.py
+++ b/testing/mozharness/scripts/desktop_unittest.py
@@ -260,11 +260,20 @@ class DesktopUnittest(TestingMixin, MercurialScript, BlobUploadMixin, MozbaseMix
         self.register_virtualenv_module(name='mock')
         self.register_virtualenv_module(name='simplejson')
 
-        requirements = os.path.join(dirs['abs_test_install_dir'],
-                                    'config',
-                                    'marionette_requirements.txt')
-        if os.path.isfile(requirements):
-            self.register_virtualenv_module(requirements=[requirements],
+        requirements_files = [
+                os.path.join(dirs['abs_test_install_dir'],
+                    'config',
+                    'marionette_requirements.txt')]
+
+        if os.path.isdir(dirs['abs_mochitest_dir']):
+            # mochitest is the only thing that needs this
+            requirements_files.append(
+                os.path.join(dirs['abs_mochitest_dir'],
+                             'websocketprocessbridge',
+                             'websocketprocessbridge_requirements.txt'))
+
+        for requirements_file in requirements_files:
+            self.register_virtualenv_module(requirements=[requirements_file],
                                             two_pass=True)
 
     def _query_symbols_url(self):
diff --git a/testing/tools/websocketprocessbridge/websocketprocessbridge_requirements.txt b/testing/tools/websocketprocessbridge/websocketprocessbridge_requirements.txt
new file mode 100644
index 000000000000..51e54809461e
--- /dev/null
+++ b/testing/tools/websocketprocessbridge/websocketprocessbridge_requirements.txt
@@ -0,0 +1,13 @@
+twisted==10.2.0
+
+# websocket adapter for twisted, might be built into twisted someday
+txws==0.9.1
+
+psutil==3.1.1
+
+# needed by txws, but pypi doesn't know about it
+six==1.10.0
+
+# Needed by iceserver
+ipaddr==2.1.11
+passlib==1.6.5