diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,6 @@
+# hpqtypes-1.9.1.2 (2021-07-29)
+* Fix compilation issues caused by ambiguos occurence of `controlT`.
+
 # hpqtypes-1.9.1.1 (2021-05-27)
 * Support GHC 9.0.
 
diff --git a/hpqtypes.cabal b/hpqtypes.cabal
--- a/hpqtypes.cabal
+++ b/hpqtypes.cabal
@@ -1,5 +1,5 @@
 name:                hpqtypes
-version:             1.9.1.1
+version:             1.9.1.2
 synopsis:            Haskell bindings to libpqtypes
 
 description:         Efficient and easy-to-use bindings to (slightly modified)
diff --git a/src/Database/PostgreSQL/PQTypes/Class.hs b/src/Database/PostgreSQL/PQTypes/Class.hs
--- a/src/Database/PostgreSQL/PQTypes/Class.hs
+++ b/src/Database/PostgreSQL/PQTypes/Class.hs
@@ -89,7 +89,3 @@
     {-# INLINE setTransactionSettings #-}
     {-# INLINE getNotification #-}
     {-# INLINE withNewConnection #-}
-
-controlT :: (MonadTransControl t, Monad (t m), Monad m)
-         => (Run t -> m (StT t a)) -> t m a
-controlT f = liftWith f >>= restoreT . return