diff --git a/phabricator/conduit.py b/phabricator/conduit.py
--- a/phabricator/conduit.py
+++ b/phabricator/conduit.py
@@ -11,6 +11,7 @@
 import json
 import os
 import time
+import warnings
 
 import urllib3
 
@@ -82,8 +83,14 @@
         if self._connection is None:
             self._connection = urllib3.PoolManager(ca_certs=self._ca_certs)
         try:
-            response = self._connection.request(
-                'POST', url, headers=headers, fields=req_data, timeout=timeout)
+            with warnings.catch_warnings():
+                if not self._ca_certs:
+                    # ignore the urllib3 certificate verification warnings
+                    warnings.simplefilter(
+                        'ignore', urllib3.exceptions.InsecureRequestWarning)
+                response = self._connection.request(
+                    'POST', url, headers=headers, fields=req_data,
+                    timeout=timeout)
         except urllib3.exceptions.HTTPError as ex:
             errno = -1
             if ex.args and util.safehasattr(ex.args[0], 'errno'):
diff --git a/tests/test-check-code-hg.t b/tests/test-check-code-hg.t
--- a/tests/test-check-code-hg.t
+++ b/tests/test-check-code-hg.t
@@ -92,7 +92,7 @@
   Skipping ctreemanifest/manifest_ptr.h it has no-che?k-code (glob)
   Skipping ctreemanifest/treemanifest.cpp it has no-che?k-code (glob)
   Skipping ctreemanifest/treemanifest.h it has no-che?k-code (glob)
-  phabricator/conduit.py:15:
+  phabricator/conduit.py:16:
    > import urllib3
    don't use urllib, use util.urlreq/util.urlerr
   Skipping tests/conduithttp.py it has no-che?k-code (glob)