diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,4 +1,10 @@
 
+50200.14.0
+==========
+
+Package changes:
+* Updated to build with `mtl-2.3.*` (thanks Ryan Scott)
+
 50200.13.0
 ==========
 
diff --git a/mattermost-api.cabal b/mattermost-api.cabal
--- a/mattermost-api.cabal
+++ b/mattermost-api.cabal
@@ -1,5 +1,5 @@
 name:                mattermost-api
-version:             50200.13.0
+version:             50200.14.0
 synopsis:            Client API for Mattermost chat system
 
 description:         Client API for Mattermost chat system.  Mattermost is a
@@ -49,7 +49,7 @@
   build-depends:       base >=4.4 && <5
                      , websockets >= 0.11.0.0
                      , stm
-                     , aeson >= 2.0.1.0 && < 2.1.0.0
+                     , aeson >= 2.0.1.0 && < 2.2.0.0
                      , connection
                      , memory
                      , resource-pool >= 0.2.3
diff --git a/test/Tests/Util.hs b/test/Tests/Util.hs
--- a/test/Tests/Util.hs
+++ b/test/Tests/Util.hs
@@ -53,13 +53,16 @@
 import qualified Control.Concurrent.STM as STM
 import Control.Concurrent (forkIO)
 import Control.Concurrent.MVar
+import Control.Monad (join, when)
+import Control.Monad.IO.Class (MonadIO(..))
 import qualified Data.Foldable as F
+import Data.Functor (void)
 import Data.Monoid ((<>))
 import qualified Data.Sequence as Seq
 import qualified Data.Text as T
 import Test.Tasty (TestTree)
 import Test.Tasty.HUnit (testCaseSteps)
-import Control.Monad.State.Lazy
+import Control.Monad.State.Lazy (evalStateT, gets, modify)
 import System.Timeout (timeout)
 
 import Network.Mattermost (ConnectionData)