diff --git a/CHANGES b/CHANGES
index 22e5f11ed..149e244dc 100644
--- a/CHANGES
+++ b/CHANGES
@@ -7,6 +7,8 @@ Version 0.10.1
 (bugfix release, release date to be decided)
 
 - Fixed regression with multiple query values for URLs (pull request ``#667``).
+- Fix issues with eventlet's monkeypatching and the builtin server (pull
+  request ``#663``).
 
 Version 0.10
 ------------
diff --git a/tests/test_serving.py b/tests/test_serving.py
index d4a4e8015..55ac707b8 100644
--- a/tests/test_serving.py
+++ b/tests/test_serving.py
@@ -10,6 +10,7 @@
 """
 import os
 import ssl
+import subprocess
 import textwrap
 
 
@@ -171,3 +172,28 @@ def real_app(environ, start_response):
     r = requests.get(server.url)
     assert r.status_code == 200
     assert r.content == b'hello'
+
+
+def test_monkeypached_sleep(tmpdir):
+    # removing the staticmethod wrapper in the definition of
+    # ReloaderLoop._sleep works most of the time, since `sleep` is a c
+    # function, and unlike python functions which are descriptors, doesn't
+    # become a method when attached to a class. however, if the user has called
+    # `eventlet.monkey_patch` before importing `_reloader`, `time.sleep` is a
+    # python function, and subsequently calling `ReloaderLoop._sleep` fails
+    # with a TypeError. This test checks that _sleep is attached correctly.
+    script = tmpdir.mkdir('app').join('test.py')
+    script.write(textwrap.dedent('''
+    import time
+
+    def sleep(secs):
+        pass
+
+    # simulate eventlet.monkey_patch by replacing the builtin sleep
+    # with a regular function before _reloader is imported
+    time.sleep = sleep
+
+    from werkzeug._reloader import ReloaderLoop
+    ReloaderLoop()._sleep(0)
+    '''))
+    subprocess.check_call(['python', str(script)])
diff --git a/werkzeug/_reloader.py b/werkzeug/_reloader.py
index e0ea56647..83716f16e 100644
--- a/werkzeug/_reloader.py
+++ b/werkzeug/_reloader.py
@@ -107,9 +107,13 @@ def _walk(node, path):
 
 
 class ReloaderLoop(object):
-    _sleep = staticmethod(time.sleep)  # monkeypatched by testsuite
     name = None
 
+    # monkeypatched by testsuite. wrapping with `staticmethod` is required in
+    # case time.sleep has been replaced by a non-c function (e.g. by
+    # `eventlet.monkey_patch`) before we get here
+    _sleep = staticmethod(time.sleep)
+
     def __init__(self, extra_files=None, interval=1):
         self.extra_files = set(os.path.abspath(x)
                                for x in extra_files or ())