diff --git a/wptrunner/browsers/b2g.py b/wptrunner/browsers/b2g.py
index 1679606713eabc..93e28b83679676 100644
--- a/wptrunner/browsers/b2g.py
+++ b/wptrunner/browsers/b2g.py
@@ -41,7 +41,7 @@ def browser_kwargs(test_environment, **kwargs):
             "no_backup": kwargs.get("b2g_no_backup", False)}
 
 
-def executor_kwargs(test_type, http_server_url, **kwargs):
+def executor_kwargs(test_type, http_server_url, cache_manager, **kwargs):
     timeout_multiplier = kwargs["timeout_multiplier"]
     if timeout_multiplier is None:
         timeout_multiplier = 2
@@ -49,6 +49,10 @@ def executor_kwargs(test_type, http_server_url, **kwargs):
     executor_kwargs = {"http_server_url": http_server_url,
                        "timeout_multiplier": timeout_multiplier,
                        "close_after_done": False}
+
+    if test_type == "reftest":
+        executor_kwargs["cache_manager"] = cache_manager
+
     return executor_kwargs
 
 
diff --git a/wptrunner/browsers/chrome.py b/wptrunner/browsers/chrome.py
index 92c58e3cb919ef..f99f2db2faf4bd 100644
--- a/wptrunner/browsers/chrome.py
+++ b/wptrunner/browsers/chrome.py
@@ -28,10 +28,11 @@ def browser_kwargs(**kwargs):
             "webdriver_binary": kwargs["webdriver_binary"]}
 
 
-def executor_kwargs(test_type, http_server_url, **kwargs):
+def executor_kwargs(test_type, http_server_url, cache_manager, **kwargs):
     from selenium.webdriver import DesiredCapabilities
 
-    executor_kwargs = base_executor_kwargs(test_type, http_server_url, **kwargs)
+    executor_kwargs = base_executor_kwargs(test_type, http_server_url,
+                                           cache_manager, **kwargs)
     executor_kwargs["close_after_done"] = True
     executor_kwargs["capabilities"] = dict(DesiredCapabilities.CHROME.items() +
                                            {"chromeOptions":
diff --git a/wptrunner/browsers/firefox.py b/wptrunner/browsers/firefox.py
index a11df67508a7c4..bb900aab7bcb3c 100644
--- a/wptrunner/browsers/firefox.py
+++ b/wptrunner/browsers/firefox.py
@@ -45,8 +45,9 @@ def browser_kwargs(**kwargs):
             "ca_certificate_path": kwargs["ssl_env"].ca_cert_path()}
 
 
-def executor_kwargs(test_type, http_server_url, **kwargs):
-    executor_kwargs = base_executor_kwargs(test_type, http_server_url, **kwargs)
+def executor_kwargs(test_type, http_server_url, cache_manager, **kwargs):
+    executor_kwargs = base_executor_kwargs(test_type, http_server_url,
+                                           cache_manager, **kwargs)
     executor_kwargs["close_after_done"] = True
     return executor_kwargs
 
diff --git a/wptrunner/browsers/servo.py b/wptrunner/browsers/servo.py
index afcc0be147d7ef..e8652da29b3c7c 100644
--- a/wptrunner/browsers/servo.py
+++ b/wptrunner/browsers/servo.py
@@ -30,8 +30,9 @@ def browser_kwargs(**kwargs):
             "interactive": kwargs["interactive"]}
 
 
-def executor_kwargs(test_type, http_server_url, **kwargs):
-    rv = base_executor_kwargs(test_type, http_server_url, **kwargs)
+def executor_kwargs(test_type, http_server_url, cache_manager, **kwargs):
+    rv = base_executor_kwargs(test_type, http_server_url,
+                              cache_manager, **kwargs)
     rv["pause_after_test"] = kwargs["pause_after_test"]
     return rv
 
diff --git a/wptrunner/environment.py b/wptrunner/environment.py
index 7da5c456bd7364..4ef21399219801 100644
--- a/wptrunner/environment.py
+++ b/wptrunner/environment.py
@@ -4,6 +4,7 @@
 
 import json
 import os
+import multiprocessing
 import socket
 import sys
 import time
@@ -97,8 +98,11 @@ def __init__(self, test_paths, ssl_env, pause_after_test, options):
         self.test_server_port = options.pop("test_server_port", True)
         self.options = options if options is not None else {}
 
+        self.cache_manager = multiprocessing.Manager()
+
     def __enter__(self):
         self.ssl_env.__enter__()
+        self.cache_manager.__enter__()
         self.setup_server_logging()
         self.setup_routes()
         self.config = self.load_config()
@@ -107,6 +111,7 @@ def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
+        self.cache_manager.__exit__(exc_type, exc_val, exc_tb)
         self.ssl_env.__exit__(exc_type, exc_val, exc_tb)
 
         for scheme, servers in self.servers.iteritems():
diff --git a/wptrunner/executors/base.py b/wptrunner/executors/base.py
index 264cefcec61fe7..d10c20e3ea7a5c 100644
--- a/wptrunner/executors/base.py
+++ b/wptrunner/executors/base.py
@@ -7,15 +7,13 @@
 import os
 import traceback
 from abc import ABCMeta, abstractmethod
-from multiprocessing import Manager
 
 from ..testrunner import Stop
 
 here = os.path.split(__file__)[0]
 
-cache_manager = Manager()
 
-def executor_kwargs(test_type, http_server_url, **kwargs):
+def executor_kwargs(test_type, http_server_url, cache_manager, **kwargs):
     timeout_multiplier = kwargs["timeout_multiplier"]
     if timeout_multiplier is None:
         timeout_multiplier = 1
diff --git a/wptrunner/wptrunner.py b/wptrunner/wptrunner.py
index 06bbfd7fbb893b..b1b9704e9ab6f9 100644
--- a/wptrunner/wptrunner.py
+++ b/wptrunner/wptrunner.py
@@ -158,6 +158,7 @@ def run_tests(config, test_paths, product, **kwargs):
                     executor_cls = executor_classes.get(test_type)
                     executor_kwargs = get_executor_kwargs(test_type,
                                                           base_server,
+                                                          test_environment.cache_manager,
                                                           **kwargs)
 
                     if executor_cls is None: