diff --git a/httpbin/core.py b/httpbin/core.py
index 9bd9521..9b22fc4 100644
--- a/httpbin/core.py
+++ b/httpbin/core.py
@@ -11,6 +11,7 @@ import base64
 import json
 import os
 import time
+import gevent
 
 import newrelic.agent
 
@@ -307,7 +308,7 @@ def delay_response(delay):
     """Returns a delayed response"""
     delay = min(delay, 10)
 
-    time.sleep(delay)
+    gevent.sleep(delay)
 
     return jsonify(get_dict(
         'url', 'args', 'form', 'data', 'origin', 'headers', 'files'))
diff --git a/httpbin/runner.py b/httpbin/runner.py
index 5dd4bf5..b004e97 100755
--- a/httpbin/runner.py
+++ b/httpbin/runner.py
@@ -11,7 +11,7 @@ gunicorn.
 
 import sys
 
-from gevent.wsgi import WSGIServer
+from gevent.pywsgi import WSGIServer
 from httpbin import app
 
 
@@ -26,4 +26,4 @@ def main():
     http_server.serve_forever()
 
 if __name__ == '__main__':
-    main()
\ No newline at end of file
+    main()