diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -40,14 +40,14 @@
 
 -- Global consumer properties
 consumerProps :: ConsumerProperties
-consumerProps = brokersList [BrokerAddress "localhost:9092"]
-             <> groupId (ConsumerGroupId "consumer_example_group")
+consumerProps = brokersList ["localhost:9092"]
+             <> groupId "consumer_example_group"
              <> noAutoCommit
              <> logLevel KafkaLogInfo
 
 -- Subscription to topics
 consumerSub :: Subscription
-consumerSub = topics [TopicName "kafka-client-example-topic"]
+consumerSub = topics ["kafka-client-example-topic"]
            <> offsetReset Earliest
 
 -- Running an example
@@ -58,7 +58,7 @@
     where
       mkConsumer = newConsumer consumerProps consumerSub
       clConsumer (Left err) = return (Left err)
-      clConsumer (Right kc) = (maybe (Right ()) Left) <$> closeConsumer kc
+      clConsumer (Right kc) = maybe (Right ()) Left <$> closeConsumer kc
       runHandler (Left err) = return (Left err)
       runHandler (Right kc) = processMessages kc
 
@@ -97,7 +97,7 @@
 
 ```haskell
 producerProps :: ProducerProperties
-producerProps = brokersList [BrokerAddress "localhost:9092"]
+producerProps = brokersList ["localhost:9092"]
              <> sendTimeout (Timeout 0)           -- for librdkafka "0" means "infinite" (see https://github.com/edenhill/librdkafka/issues/2015)
 ```
 
@@ -108,7 +108,7 @@
 
 ```haskell
 producerProps :: ProducerProperties
-producerProps = brokersList [BrokerAddress "localhost:9092"]
+producerProps = brokersList ["localhost:9092"]
              <> setCallback (deliveryCallback print)
 ```
 
@@ -126,12 +126,12 @@
 
 -- Global producer properties
 producerProps :: ProducerProperties
-producerProps = brokersList [BrokerAddress "localhost:9092"]
+producerProps = brokersList ["localhost:9092"]
              <> logLevel KafkaLogDebug
 
 -- Topic to send messages to
 targetTopic :: TopicName
-targetTopic = TopicName "kafka-client-example-topic"
+targetTopic = "kafka-client-example-topic"
 
 -- Run an example
 runProducerExample :: IO ()
diff --git a/example/ConsumerExample.hs b/example/ConsumerExample.hs
--- a/example/ConsumerExample.hs
+++ b/example/ConsumerExample.hs
@@ -11,8 +11,8 @@
 
 -- Global consumer properties
 consumerProps :: ConsumerProperties
-consumerProps = brokersList [BrokerAddress "localhost:9092"]
-             <> groupId (ConsumerGroupId "consumer_example_group")
+consumerProps = brokersList ["localhost:9092"]
+             <> groupId "consumer_example_group"
              <> noAutoCommit
              <> setCallback (rebalanceCallback printingRebalanceCallback)
              <> setCallback (offsetCommitCallback printingOffsetCallback)
@@ -20,7 +20,7 @@
 
 -- Subscription to topics
 consumerSub :: Subscription
-consumerSub = topics [TopicName "kafka-client-example-topic"]
+consumerSub = topics ["kafka-client-example-topic"]
            <> offsetReset Earliest
 
 -- Running an example
@@ -32,7 +32,7 @@
     where
       mkConsumer = newConsumer consumerProps consumerSub
       clConsumer (Left err) = return (Left err)
-      clConsumer (Right kc) = (maybe (Right ()) Left) <$> closeConsumer kc
+      clConsumer (Right kc) = maybe (Right ()) Left <$> closeConsumer kc
       runHandler (Left err) = return (Left err)
       runHandler (Right kc) = processMessages kc
 
diff --git a/example/ProducerExample.hs b/example/ProducerExample.hs
--- a/example/ProducerExample.hs
+++ b/example/ProducerExample.hs
@@ -16,14 +16,14 @@
 
 -- Global producer properties
 producerProps :: ProducerProperties
-producerProps = brokersList [BrokerAddress "localhost:9092"]
+producerProps = brokersList ["localhost:9092"]
              <> sendTimeout (Timeout 10000)
              <> setCallback (deliveryCallback print)
              <> logLevel KafkaLogDebug
 
 -- Topic to send messages to
 targetTopic :: TopicName
-targetTopic = TopicName "kafka-client-example-topic"
+targetTopic = "kafka-client-example-topic"
 
 mkMessage :: Maybe ByteString -> Maybe ByteString -> ProducerRecord
 mkMessage k v = ProducerRecord
diff --git a/hw-kafka-client.cabal b/hw-kafka-client.cabal
--- a/hw-kafka-client.cabal
+++ b/hw-kafka-client.cabal
@@ -1,7 +1,7 @@
 cabal-version: 2.2
 
 name:                   hw-kafka-client
-version:                4.0.0
+version:                4.0.1
 synopsis:               Kafka bindings for Haskell
 description:            Apache Kafka bindings backed by the librdkafka C library.
                         .
diff --git a/src/Kafka/Consumer.hs b/src/Kafka/Consumer.hs
--- a/src/Kafka/Consumer.hs
+++ b/src/Kafka/Consumer.hs
@@ -15,7 +15,7 @@
 -- 
 -- -- Global consumer properties
 -- consumerProps :: 'ConsumerProperties'
--- consumerProps = 'brokersList' ['BrokerAddress' "localhost:9092"]
+-- consumerProps = 'brokersList' ["localhost:9092"]
 --              <> 'groupId' ('ConsumerGroupId' "consumer_example_group")
 --              <> 'noAutoCommit'
 --              <> 'logLevel' 'KafkaLogInfo'
diff --git a/src/Kafka/Consumer/ConsumerProperties.hs b/src/Kafka/Consumer/ConsumerProperties.hs
--- a/src/Kafka/Consumer/ConsumerProperties.hs
+++ b/src/Kafka/Consumer/ConsumerProperties.hs
@@ -77,7 +77,7 @@
 -- | Set the <https://kafka.apache.org/documentation/#bootstrap.servers list of brokers> to contact to connect to the Kafka cluster.
 brokersList :: [BrokerAddress] -> ConsumerProperties
 brokersList bs =
-  let bs' = Text.intercalate "," ((\(BrokerAddress x) -> x) <$> bs)
+  let bs' = Text.intercalate "," (unBrokerAddress <$> bs)
    in extraProps $ M.fromList [("bootstrap.servers", bs')]
 
 -- | Set the <https://kafka.apache.org/documentation/#auto.commit.interval.ms auto commit interval> and enables <https://kafka.apache.org/documentation/#enable.auto.commit auto commit>.
diff --git a/src/Kafka/Consumer/Types.hs b/src/Kafka/Consumer/Types.hs
--- a/src/Kafka/Consumer/Types.hs
+++ b/src/Kafka/Consumer/Types.hs
@@ -1,5 +1,6 @@
-{-# LANGUAGE DeriveDataTypeable #-}
-{-# LANGUAGE DeriveGeneric      #-}
+{-# LANGUAGE DeriveDataTypeable         #-}
+{-# LANGUAGE DeriveGeneric              #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
 
 -----------------------------------------------------------------------------
 -- |
@@ -37,6 +38,7 @@
 import Data.Bifunctor       (Bifunctor (..))
 import Data.Bitraversable   (Bitraversable (..), bimapM, bisequence)
 import Data.Int             (Int64)
+import Data.String          (IsString)
 import Data.Text            (Text)
 import Data.Typeable        (Typeable)
 import GHC.Generics         (Generic)
@@ -62,7 +64,9 @@
 -- | Consumer group ID. Different consumers with the same consumer group ID will get assigned different partitions of each subscribed topic. 
 -- 
 -- See <https://kafka.apache.org/documentation/#group.id Kafka documentation on consumer group>
-newtype ConsumerGroupId = ConsumerGroupId { unConsumerGroupId :: Text } deriving (Show, Ord, Eq, Generic)
+newtype ConsumerGroupId = ConsumerGroupId
+  { unConsumerGroupId :: Text
+  } deriving (Show, Ord, Eq, IsString, Generic)
 
 -- | A message offset in a partition
 newtype Offset          = Offset { unOffset :: Int64 } deriving (Show, Eq, Ord, Read, Generic)
diff --git a/src/Kafka/Internal/RdKafka.chs b/src/Kafka/Internal/RdKafka.chs
--- a/src/Kafka/Internal/RdKafka.chs
+++ b/src/Kafka/Internal/RdKafka.chs
@@ -415,7 +415,7 @@
     withForeignPtr conf $ \c -> rdKafkaConfSetLogCb' c cb'
 
 ---- Stats Callback
-type StatsCallback' = Ptr RdKafkaT -> CString -> CSize -> Word8Ptr -> IO ()
+type StatsCallback' = Ptr RdKafkaT -> CString -> CSize -> Word8Ptr -> IO CInt
 type StatsCallback = Ptr RdKafkaT -> ByteString -> IO ()
 
 foreign import ccall safe "wrapper"
@@ -426,12 +426,12 @@
 
 rdKafkaConfSetStatsCb :: RdKafkaConfTPtr -> StatsCallback -> IO ()
 rdKafkaConfSetStatsCb conf cb = do
-    cb' <- mkStatsCallback $ \k j jl _ -> BS.packCStringLen (j, cIntConv jl) >>= cb k
+    cb' <- mkStatsCallback $ \k j jl _ -> BS.packCStringLen (j, cIntConv jl) >>= cb k >> pure 0
     withForeignPtr conf $ \c -> rdKafkaConfSetStatsCb' c cb'
     return ()
 
 ---- Socket Callback
-type SocketCallback = Int -> Int -> Int -> Word8Ptr -> IO ()
+type SocketCallback = Int -> Int -> Int -> Word8Ptr -> IO CInt
 
 foreign import ccall safe "wrapper"
     mkSocketCallback :: SocketCallback -> IO (FunPtr SocketCallback)
@@ -442,7 +442,7 @@
 rdKafkaConfSetSocketCb :: RdKafkaConfTPtr -> SocketCallback -> IO ()
 rdKafkaConfSetSocketCb conf cb = do
     cb' <- mkSocketCallback cb
-    withForeignPtr conf $ \c -> rdKafkaConfSetSocketCb' c cb'
+    withForeignPtr conf $ \c -> rdKafkaConfSetSocketCb' c cb' >> pure 0
     return ()
 
 {#fun rd_kafka_conf_set_opaque as ^
diff --git a/src/Kafka/Internal/Shared.hs b/src/Kafka/Internal/Shared.hs
--- a/src/Kafka/Internal/Shared.hs
+++ b/src/Kafka/Internal/Shared.hs
@@ -35,8 +35,8 @@
 
 pollEvents :: HasKafka a => a -> Maybe Timeout -> IO ()
 pollEvents a tm =
-  let timeout = maybe 0 (\(Timeout ms) -> ms) tm
-      (Kafka k) = getKafka a
+  let timeout = maybe 0 unTimeout tm
+      Kafka k = getKafka a
   in void (rdKafkaPoll k timeout)
 
 word8PtrToBS :: Int -> Word8Ptr -> IO BS.ByteString
diff --git a/src/Kafka/Metadata.hs b/src/Kafka/Metadata.hs
--- a/src/Kafka/Metadata.hs
+++ b/src/Kafka/Metadata.hs
@@ -260,8 +260,8 @@
     { pmPartitionId     = PartitionId (id'RdKafkaMetadataPartitionT pm)
     , pmError           = kafkaErrorToMaybe $ KafkaResponseError (err'RdKafkaMetadataPartitionT pm)
     , pmLeader          = BrokerId (leader'RdKafkaMetadataPartitionT pm)
-    , pmReplicas        = (BrokerId . fromIntegral) <$> reps
-    , pmInSyncReplicas  = (BrokerId . fromIntegral) <$> isrs
+    , pmReplicas        = BrokerId . fromIntegral <$> reps
+    , pmInSyncReplicas  = BrokerId . fromIntegral <$> isrs
     }
 
 
@@ -296,4 +296,4 @@
   "Stable"             -> GroupStable
   "Dead"               -> GroupDead
   "Empty"              -> GroupEmpty
-  _                    -> error $ "Unknown group state: " <> (Text.unpack s)
+  _                    -> error $ "Unknown group state: " <> Text.unpack s
diff --git a/src/Kafka/Producer.hs b/src/Kafka/Producer.hs
--- a/src/Kafka/Producer.hs
+++ b/src/Kafka/Producer.hs
@@ -15,7 +15,7 @@
 -- 
 -- -- Global producer properties
 -- producerProps :: 'ProducerProperties'
--- producerProps = 'brokersList' ['BrokerAddress' "localhost:9092"]
+-- producerProps = 'brokersList' ["localhost:9092"]
 --              <> 'logLevel' 'KafkaLogDebug'
 -- 
 -- -- Topic to send messages to
diff --git a/src/Kafka/Producer/Convert.hs b/src/Kafka/Producer/Convert.hs
--- a/src/Kafka/Producer/Convert.hs
+++ b/src/Kafka/Producer/Convert.hs
@@ -28,13 +28,13 @@
 {-# INLINE producePartitionCInt #-}
 
 handleProduceErr :: Int -> IO (Maybe KafkaError)
-handleProduceErr (- 1) = (Just . kafkaRespErr) <$> getErrno
+handleProduceErr (- 1) = Just . kafkaRespErr <$> getErrno
 handleProduceErr 0 = return Nothing
 handleProduceErr _ = return $ Just KafkaInvalidReturnValue
 {-# INLINE handleProduceErr #-}
 
 handleProduceErr' :: Int -> IO (Either KafkaError ())
-handleProduceErr' (- 1) = (Left . kafkaRespErr) <$> getErrno
+handleProduceErr' (- 1) = Left . kafkaRespErr <$> getErrno
 handleProduceErr' 0 = return (Right ())
 handleProduceErr' _ = return $ Left KafkaInvalidReturnValue
 {-# INLINE handleProduceErr' #-}
diff --git a/src/Kafka/Producer/ProducerProperties.hs b/src/Kafka/Producer/ProducerProperties.hs
--- a/src/Kafka/Producer/ProducerProperties.hs
+++ b/src/Kafka/Producer/ProducerProperties.hs
@@ -60,7 +60,7 @@
 -- | Set the <https://kafka.apache.org/documentation/#bootstrap.servers list of brokers> to contact to connect to the Kafka cluster.
 brokersList :: [BrokerAddress] -> ProducerProperties
 brokersList bs =
-  let bs' = Text.intercalate "," ((\(BrokerAddress x) -> x) <$> bs)
+  let bs' = Text.intercalate "," (unBrokerAddress <$> bs)
    in extraProps $ M.fromList [("bootstrap.servers", bs')]
 
 -- | Set the producer callback.
diff --git a/src/Kafka/Types.hs b/src/Kafka/Types.hs
--- a/src/Kafka/Types.hs
+++ b/src/Kafka/Types.hs
@@ -29,6 +29,7 @@
 
 import Control.Exception      (Exception (..))
 import Data.Int               (Int64)
+import Data.String            (IsString)
 import Data.Text              (Text, isPrefixOf)
 import Data.Typeable          (Typeable)
 import GHC.Generics           (Generic)
@@ -46,7 +47,9 @@
 -- | Client ID used by Kafka to better track requests
 -- 
 -- See <https://kafka.apache.org/documentation/#client.id Kafka documentation on client ID>
-newtype ClientId    = ClientId { unClientId :: Text } deriving (Show, Eq, Ord, Generic)
+newtype ClientId = ClientId
+  { unClientId :: Text
+  } deriving (Show, Eq, IsString, Ord, Generic)
 
 -- | Batch size used for polling
 newtype BatchSize   = BatchSize { unBatchSize :: Int } deriving (Show, Read, Eq, Ord, Num, Generic)
@@ -63,9 +66,9 @@
 -- any topic name in the topics list that is prefixed with @^@ will
 -- be regex-matched to the full list of topics in the cluster and matching
 -- topics will be added to the subscription list.
-newtype TopicName =
-    TopicName { unTopicName :: Text } -- ^ a simple topic name or a regex if started with @^@
-    deriving (Show, Eq, Ord, Read, Generic)
+newtype TopicName = TopicName
+  { unTopicName :: Text -- ^ a simple topic name or a regex if started with @^@
+  } deriving (Show, Eq, Ord, IsString, Read, Generic)
 
 -- | Deduce the type of a topic from its name, by checking if it starts with a double underscore "\__"
 topicType :: TopicName -> TopicType
@@ -74,7 +77,9 @@
 {-# INLINE topicType #-}
 
 -- | Kafka broker address string (e.g. @broker1:9092@)
-newtype BrokerAddress = BrokerAddress { unBrokerAddress :: Text } deriving (Show, Eq, Generic)
+newtype BrokerAddress = BrokerAddress
+  { unBrokerAddress :: Text
+  } deriving (Show, Eq, IsString, Generic)
 
 -- | Timeout in milliseconds
 newtype Timeout = Timeout { unTimeout :: Int } deriving (Show, Eq, Read, Generic)
diff --git a/tests-it/Kafka/IntegrationSpec.hs b/tests-it/Kafka/IntegrationSpec.hs
--- a/tests-it/Kafka/IntegrationSpec.hs
+++ b/tests-it/Kafka/IntegrationSpec.hs
@@ -118,7 +118,7 @@
                 var <- newEmptyMVar
                 let
                   msg = ProducerRecord
-                    { prTopic = TopicName "callback-topic"
+                    { prTopic = "callback-topic"
                     , prPartition = UnassignedPartition
                     , prKey = Nothing
                     , prValue = Just "test from producer"
@@ -136,7 +136,7 @@
         specWithConsumer "Run consumer with sync polling" (consumerProps <> groupId (makeGroupId "sync") <> callbackPollMode CallbackPollModeSync) runConsumerSpec
 
     describe "Kafka.Consumer.BatchSpec" $ do
-        specWithConsumer "Batch consumer" (consumerProps <> groupId (ConsumerGroupId "batch-consumer")) $ do
+        specWithConsumer "Batch consumer" (consumerProps <> groupId "batch-consumer") $ do
             it "should consume first batch" $ \k -> do
                 res <- pollMessageBatch k (Timeout 1000) (BatchSize 5)
                 length res `shouldBe` 5
@@ -232,8 +232,8 @@
   it "should return topic metadata" $ \k -> do
     res <- topicMetadata k (Timeout 1000) testTopic
     res `shouldSatisfy` isRight
-    (length . kmBrokers) <$> res `shouldBe` Right 1
-    (length . kmTopics) <$> res `shouldBe` Right 1
+    length . kmBrokers <$> res `shouldBe` Right 1
+    length . kmTopics <$> res `shouldBe` Right 1
 
   it "should describe all consumer groups" $ \k -> do
     res <- allConsumerGroupsInfo k (Timeout 1000)
@@ -248,7 +248,7 @@
     fmap giGroup <$> res `shouldBe` Right [testGroupId]
 
   it "should describe non-existent consumer group" $ \k -> do
-    res <- consumerGroupInfo k (Timeout 1000) (ConsumerGroupId "does-not-exist")
+    res <- consumerGroupInfo k (Timeout 1000) "does-not-exist"
     res `shouldBe` Right []
 
   it "should read topic offsets for time" $ \k -> do
diff --git a/tests-it/Kafka/TestEnv.hs b/tests-it/Kafka/TestEnv.hs
--- a/tests-it/Kafka/TestEnv.hs
+++ b/tests-it/Kafka/TestEnv.hs
@@ -24,12 +24,12 @@
 
 brokerAddress :: BrokerAddress
 brokerAddress = unsafePerformIO $
-  (BrokerAddress . Text.pack) <$> getEnv "KAFKA_TEST_BROKER" `catch` \(_ :: SomeException) -> return "localhost:9092"
+  BrokerAddress . Text.pack <$> getEnv "KAFKA_TEST_BROKER" `catch` \(_ :: SomeException) -> return "localhost:9092"
 {-# NOINLINE brokerAddress #-}
 
 testTopic :: TopicName
 testTopic = unsafePerformIO $
-  (TopicName . Text.pack) <$> getEnv "KAFKA_TEST_TOPIC" `catch` \(_ :: SomeException) -> return $ testPrefix <> "-topic"
+  TopicName . Text.pack <$> getEnv "KAFKA_TEST_TOPIC" `catch` \(_ :: SomeException) -> return $ testPrefix <> "-topic"
 {-# NOINLINE testTopic #-}
 
 testGroupId :: ConsumerGroupId
diff --git a/tests/Kafka/Consumer/ConsumerRecordMapSpec.hs b/tests/Kafka/Consumer/ConsumerRecordMapSpec.hs
--- a/tests/Kafka/Consumer/ConsumerRecordMapSpec.hs
+++ b/tests/Kafka/Consumer/ConsumerRecordMapSpec.hs
@@ -15,7 +15,7 @@
 
 testRecord :: ConsumerRecord (Maybe Text) (Maybe Text)
 testRecord = ConsumerRecord
-  { crTopic     = TopicName "some-topic"
+  { crTopic     = "some-topic"
   , crPartition = PartitionId 0
   , crOffset    = Offset 5
   , crTimestamp = NoTimestamp
diff --git a/tests/Kafka/Consumer/ConsumerRecordTraverseSpec.hs b/tests/Kafka/Consumer/ConsumerRecordTraverseSpec.hs
--- a/tests/Kafka/Consumer/ConsumerRecordTraverseSpec.hs
+++ b/tests/Kafka/Consumer/ConsumerRecordTraverseSpec.hs
@@ -17,7 +17,7 @@
 
 testRecord :: ConsumerRecord Text Text
 testRecord = ConsumerRecord
-  { crTopic     = TopicName "some-topic"
+  { crTopic     = "some-topic"
   , crPartition = PartitionId 0
   , crOffset    = Offset 5
   , crTimestamp = NoTimestamp