diff --git a/tests/test_dedup.py b/tests/test_dedup.py
index 124efb5..eea3ccd 100644
--- a/tests/test_dedup.py
+++ b/tests/test_dedup.py
@@ -4,43 +4,43 @@ from warcprox.dedup import CdxServerDedup
 
 def test_cdx_dedup():
     # Mock CDX Server responses to simulate found, not found and errors.
-    with mock.patch('warcprox.dedup.CdxServerDedup.http_pool.request') as request:
-        url = "http://example.com"
-        # not found case
-        result = mock.Mock()
-        result.status = 200
-        result.data = b'20170101020405 test'
-        request.return_value = result
-        cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
-        res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
-                                url=url)
-        assert res is None
+    url = "http://example.com"
+    # not found case
+    result = mock.Mock()
+    result.status = 200
+    result.data = b'20170101020405 test'
+    cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
+    cdx_server.http_pool.request = mock.MagicMock(return_value=result)
+    res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
+                            url=url)
+    assert res is None
 
-        # found case
-        result = mock.Mock()
-        result.status = 200
-        result.data = b'20170203040503 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A'
-        request.return_value = result
-        cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
-        res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
-                                url=url)
-        assert res["date"] == b"2017-02-03T04:05:03Z"
+    # found case
+    result = mock.Mock()
+    result.status = 200
+    result.data = b'20170203040503 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A'
+    cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
+    cdx_server.http_pool.request = mock.MagicMock(return_value=result)
+    res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
+                            url=url)
+    assert res["date"] == b"2017-02-03T04:05:03Z"
 
-        # invalid CDX result status code
-        result = mock.Mock()
-        result.status = 400
-        result.data = b'20170101020405 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A'
-        request.return_value = result
-        cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
-        res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
-                                url=url)
-        assert res is None
-        # invalid CDX result content
-        result = mock.Mock()
-        result.status = 200
-        result.data = b'InvalidExceptionResult'
-        request.return_value = result
-        cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
-        res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
-                                url=url)
-        assert res is None
+    # invalid CDX result status code
+    result = mock.Mock()
+    result.status = 400
+    result.data = b'20170101020405 B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A'
+    cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
+    cdx_server.http_pool.request = mock.MagicMock(return_value=result)
+    res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
+                            url=url)
+    assert res is None
+
+    # invalid CDX result content
+    result = mock.Mock()
+    result.status = 200
+    result.data = b'InvalidExceptionResult'
+    cdx_server = CdxServerDedup(cdx_url="dummy-cdx-server-url")
+    cdx_server.http_pool.request = mock.MagicMock(return_value=result)
+    res = cdx_server.lookup(digest_key="B2LTWWPUOYAH7UIPQ7ZUPQ4VMBSVC36A",
+                            url=url)
+    assert res is None
diff --git a/warcprox/dedup.py b/warcprox/dedup.py
index f21e1df..45b8142 100644
--- a/warcprox/dedup.py
+++ b/warcprox/dedup.py
@@ -185,12 +185,12 @@ class CdxServerDedup(object):
     """Query a CDX server to perform deduplication.
     """
     logger = logging.getLogger("warcprox.dedup.CdxServerDedup")
-    http_pool = urllib3.PoolManager()
 
     def __init__(self, cdx_url="https://web.archive.org/cdx/search",
-                 options=warcprox.Options()):
+                 maxsize=200, options=warcprox.Options()):
         self.cdx_url = cdx_url
         self.options = options
+        self.http_pool = urllib3.PoolManager(maxsize=maxsize)
 
     def start(self):
         pass
diff --git a/warcprox/main.py b/warcprox/main.py
index 8bfc3c4..065bd63 100644
--- a/warcprox/main.py
+++ b/warcprox/main.py
@@ -225,7 +225,9 @@ def init_controller(args):
     elif args.rethinkdb_trough_db_url:
         dedup_db = warcprox.dedup.TroughDedupDb(options)
     elif args.cdxserver_dedup:
-        dedup_db = warcprox.dedup.CdxServerDedup(cdx_url=args.cdxserver_dedup)
+        cdxserver_maxsize = args.writer_threads or 200
+        dedup_db = warcprox.dedup.CdxServerDedup(cdx_url=args.cdxserver_dedup,
+                                                 maxsize=cdxserver_maxsize)
     elif args.dedup_db_file in (None, '', '/dev/null'):
         logging.info('deduplication disabled')
         dedup_db = None