diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,8 @@
+# consumers-2.1.2.0 (2018-07-11)
+
+* Support hpqtypes-1.6.0.0.
+* Drop support for GHC < 8.
+
 # consumers-2.1.1.0 (2018-03-18)
 
 * GHC 8.4.1 support.
diff --git a/consumers.cabal b/consumers.cabal
--- a/consumers.cabal
+++ b/consumers.cabal
@@ -1,5 +1,5 @@
 name:               consumers
-version:            2.1.1.0
+version:            2.1.2.0
 synopsis:           Concurrent PostgreSQL data consumers
 
 description:        Library for setting up concurrent consumers of data
@@ -18,8 +18,7 @@
 category:           Concurrency, Database
 build-type:         Simple
 cabal-version:      >=1.10
-tested-with:        GHC == 7.10.3, GHC == 8.0.2, GHC == 8.2.2,
-                    GHC == 8.4.1
+tested-with:        GHC == 8.0.2, GHC == 8.2.2, GHC == 8.4.3
 
 Source-repository head
   Type:             git
@@ -32,11 +31,11 @@
                     Database.PostgreSQL.Consumers.Components,
                     Database.PostgreSQL.Consumers.Utils
 
-  build-depends:    base <5,
+  build-depends:    base >4 && <5,
                     containers,
                     exceptions,
                     extra,
-                    hpqtypes >= 1.5,
+                    hpqtypes >= 1.6 && < 1.7,
                     lifted-base,
                     lifted-threads,
                     log-base >= 0.7,
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
@@ -1,3 +1,4 @@
+{-# LANGUAGE TypeApplications #-}
 module Database.PostgreSQL.Consumers.Consumer (
     ConsumerID
   , registerConsumer
@@ -18,7 +19,10 @@
 
 -- | ID of a consumer.
 newtype ConsumerID = ConsumerID Int64
-  deriving (Eq, Ord, PQFormat)
+  deriving (Eq, Ord)
+
+instance PQFormat ConsumerID where
+  pqFormat = pqFormat @Int64
 instance FromSQL ConsumerID where
   type PQBase ConsumerID = PQBase Int64
   fromSQL mbase = ConsumerID <$> fromSQL mbase