diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+# consumers-2.1.1.0 (2018-03-18)
+
+* GHC 8.4.1 support.
+
 # consumers-2.1.0.0 (2017-09-18)
 
 * Added a `MonadTime` constraint to `runConsumer`. The `currentTime`
diff --git a/consumers.cabal b/consumers.cabal
--- a/consumers.cabal
+++ b/consumers.cabal
@@ -1,5 +1,5 @@
 name:               consumers
-version:            2.1.0.0
+version:            2.1.1.0
 synopsis:           Concurrent PostgreSQL data consumers
 
 description:        Library for setting up concurrent consumers of data
@@ -12,12 +12,14 @@
 extra-source-files: CHANGELOG.md, README.md
 author:             Scrive AB
 maintainer:         Andrzej Rybczak <andrzej@rybczak.net>,
-                    Jonathan Jouty <jonathan@scrive.com>
+                    Jonathan Jouty <jonathan@scrive.com>,
+                    Mikhail Glushenkov <mikhail@scrive.com>
 copyright:          Scrive AB
 category:           Concurrency, Database
 build-type:         Simple
 cabal-version:      >=1.10
-tested-with:        GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.1
+tested-with:        GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2,
+                    GHC == 8.4.1
 
 Source-repository head
   Type:             git
@@ -34,7 +36,7 @@
                     containers,
                     exceptions,
                     extra,
-                    hpqtypes >=1.5,
+                    hpqtypes >= 1.5,
                     lifted-base,
                     lifted-threads,
                     log-base >= 0.7,
diff --git a/example/Example.hs b/example/Example.hs
--- a/example/Example.hs
+++ b/example/Example.hs
@@ -24,6 +24,8 @@
 
 import qualified Data.Text as T
 
+-- | Main application monad. See the 'log-base' and the 'hpqtypes'
+-- packages for documentation on 'DBT' and 'LogT'.
 type AppM a = DBT (LogT IO) a
 
 main :: IO ()
@@ -36,19 +38,29 @@
   let connSettings                = def { csConnInfo = T.pack connString }
       ConnectionSource connSource = simpleSource connSettings
 
+  -- Monad stack initialisation.
   withSimpleStdOutLogger $ \logger ->
     runLogT "consumers-example" logger $
     runDBT connSource {- transactionSettings -} def $ do
+
+        -- Initialise.
         createTables
+
+        -- Create a consumer, put ten jobs into its queue, and wait
+        -- for it to finish. 'runConsumer' returns a finaliser that is
+        -- invoked by 'finalize' after the 'putJob' loop.
         finalize (localDomain "process" $
-                  runConsumer consumerConfig connSource) $ do
+                  runConsumer consumerConfig connSource) $
           forM_ [(0::Int)..10] $ \_ -> do
             putJob
             liftIO $ threadDelay (1 * 1000000) -- 1 sec
+
+        -- Clean up.
         dropTables
 
     where
 
+      -- How to connect to DB.
       defaultConnString =
         "postgresql://postgres@localhost/travis_ci_test"
 
@@ -59,17 +71,19 @@
 
       createTables :: AppM ()
       createTables = do
-        migrateDatabase {- options -} [] {- extensions -} [] {- domains -} []
+        migrateDatabase {- options -} def {- extensions -} [] {- domains -} []
           tables migrations
-        checkDatabase {- domains -} [] tables
+        checkDatabase {- options -} def {- domains -} [] tables
 
       dropTables :: AppM ()
       dropTables = do
-        migrateDatabase {- options -} [] {- extensions -} [] {- domains -} []
+        migrateDatabase {- options -} def {- extensions -} [] {- domains -} []
           {- tables -} []
           [ dropTableMigration jobsTable
           , dropTableMigration consumersTable ]
 
+      -- Configuration of a consumer. See
+      -- 'Database.PostgreSQL.Consumers.Config.ConsumerConfig'.
       consumerConfig = ConsumerConfig
         { ccJobsTable           = "consumers_example_jobs"
         , ccConsumersTable      = "consumers_example_consumers"
@@ -83,6 +97,7 @@
         , ccOnException         = handleException
         }
 
+      -- Add a job to the consumer's queue.
       putJob :: AppM ()
       putJob = localDomain "put" $ do
         logInfo_ "putJob"
@@ -91,11 +106,15 @@
           <> "VALUES (NOW(), NULL, NULL, 0, 'hello')"
         commit
 
+      -- Invoked when a job is ready to be processed.
       processJob :: (Int64, T.Text) -> AppM Result
       processJob (_idx, msg) = do
         logInfo_ msg
         return (Ok Remove)
 
+      -- Invoked when 'processJob' throws an exception. Can handle
+      -- failure in different ways, such as: remove the job from the
+      -- queue, mark it as processed, or schedule it for rerun.
       handleException :: SomeException -> (Int64, T.Text) -> AppM Action
       handleException exc (idx, _msg) = do
         logAttention_ $
@@ -103,6 +122,8 @@
         return . RerunAfter $ imicroseconds 500000
 
 
+-- | Table where jobs are stored. See
+-- 'Database.PostgreSQL.Consumers.Config.ConsumerConfig'.
 jobsTable :: Table
 jobsTable =
   tblTable
@@ -132,6 +153,8 @@
     ]
   }
 
+-- | Table where registered consumers are stored. See
+-- 'Database.PostgreSQL.Consumers.Config.ConsumerConfig'.
 consumersTable :: Table
 consumersTable =
   tblTable
diff --git a/src/Database/PostgreSQL/Consumers/Consumer.hs b/src/Database/PostgreSQL/Consumers/Consumer.hs
--- a/src/Database/PostgreSQL/Consumers/Consumer.hs
+++ b/src/Database/PostgreSQL/Consumers/Consumer.hs
@@ -28,7 +28,7 @@
 
 instance Show ConsumerID where
   showsPrec p (ConsumerID n) = showsPrec p n
- 
+
 -- | Register consumer in the consumers table,
 -- so that it can reserve jobs using acquired ID.
 registerConsumer
diff --git a/test/Test.hs b/test/Test.hs
--- a/test/Test.hs
+++ b/test/Test.hs
@@ -119,13 +119,13 @@
 
       createTables :: TestEnv ()
       createTables = do
-        migrateDatabase {- options -} [] {- extensions -} [] {- domains -} []
+        migrateDatabase {- options -} def {- extensions -} [] {- domains -} []
           tables migrations
-        checkDatabase {- domains -} [] tables
+        checkDatabase {- options -} def {- domains -} [] tables
 
       dropTables :: TestEnv ()
       dropTables = do
-        migrateDatabase {- options -} [] {- extensions -} [] {- domains -} []
+        migrateDatabase {- options -} def {- extensions -} [] {- domains -} []
           {- tables -} []
           [ dropTableMigration jobsTable
           , dropTableMigration consumersTable ]