diff --git a/Network/HTTP/Conduit.hs b/Network/HTTP/Conduit.hs
--- a/Network/HTTP/Conduit.hs
+++ b/Network/HTTP/Conduit.hs
@@ -104,6 +104,7 @@
     , ManagerSettings
     , managerConnCount
     , managerCheckCerts
+    , managerCertStore
       -- *** Defaults
     , defaultCheckCerts
       -- * Cookies
diff --git a/Network/HTTP/Conduit/Manager.hs b/Network/HTTP/Conduit/Manager.hs
--- a/Network/HTTP/Conduit/Manager.hs
+++ b/Network/HTTP/Conduit/Manager.hs
@@ -70,6 +70,8 @@
       -- ^ Number of connections to a single host to keep alive. Default: 10.
     , managerCheckCerts :: CertificateStore -> S8.ByteString -> [X509] -> IO CertificateUsage
       -- ^ Check if the server certificate is valid. Only relevant for HTTPS.
+    , managerCertStore :: IO CertificateStore
+      -- ^ Load up the certificate store. By default uses the system store.
     }
 
 type X509Encoded = L.ByteString
@@ -78,6 +80,7 @@
     def = ManagerSettings
         { managerConnCount = 10
         , managerCheckCerts = defaultCheckCerts
+        , managerCertStore = getSystemCertificateStore
         }
 
 -- | Check certificates using the operating system's certificate checker.
@@ -147,7 +150,7 @@
 -- | Create a 'Manager'. You must manually call 'closeManager' to shut it down.
 newManager :: ManagerSettings -> IO Manager
 newManager ms = do
-    certStore <- getSystemCertificateStore
+    certStore <- managerCertStore ms
     mapRef <- I.newIORef (Just Map.empty)
     certCache <- I.newIORef Map.empty
     _ <- forkIO $ reap mapRef certCache
diff --git a/http-conduit.cabal b/http-conduit.cabal
--- a/http-conduit.cabal
+++ b/http-conduit.cabal
@@ -1,5 +1,5 @@
 name:            http-conduit
-version:         1.8.1
+version:         1.8.2
 license:         BSD3
 license-file:    LICENSE
 author:          Michael Snoyman <michael@snoyman.com>