diff --git a/hasql.cabal b/hasql.cabal
--- a/hasql.cabal
+++ b/hasql.cabal
@@ -1,7 +1,7 @@
 name:
   hasql
 version:
-  0.19.3.1
+  0.19.3.2
 category:
   Hasql, Database, PostgreSQL
 synopsis:
diff --git a/library/Hasql/Private/Session.hs b/library/Hasql/Private/Session.hs
--- a/library/Hasql/Private/Session.hs
+++ b/library/Hasql/Private/Session.hs
@@ -4,6 +4,7 @@
 import Hasql.Prelude
 import qualified Database.PostgreSQL.LibPQ as LibPQ
 import qualified Hasql.Decoders.Results as Decoders.Results
+import qualified Hasql.Decoders.Result as Decoders.Result
 import qualified Hasql.Settings as Settings
 import qualified Hasql.Private.IO as IO
 import qualified Hasql.Private.Query as Query
@@ -30,8 +31,13 @@
 sql :: ByteString -> Session ()
 sql sql =
   Session $ ReaderT $ \(Connection.Connection pqConnectionRef integerDatetimes registry) ->
-    EitherT $ fmap (mapLeft unsafeCoerce) $ withMVar pqConnectionRef $ \pqConnection ->
-      IO.sendNonparametricQuery pqConnection sql
+    EitherT $ fmap (mapLeft unsafeCoerce) $ withMVar pqConnectionRef $ \pqConnection -> runEitherT $ do
+      EitherT $ IO.sendNonparametricQuery pqConnection sql
+      EitherT $ IO.getResults pqConnection integerDatetimes decoder
+  where
+    decoder =
+      Decoders.Results.single $
+      Decoders.Result.unit
 
 -- |
 -- Parameters and a specification of the parametric query to apply them to.
diff --git a/tasty/Main.hs b/tasty/Main.hs
--- a/tasty/Main.hs
+++ b/tasty/Main.hs
@@ -1,6 +1,6 @@
 module Main where
 
-import Main.Prelude hiding (assert, isRight, isLeft)
+import Main.Prelude hiding (assert)
 import Test.QuickCheck.Instances
 import Test.Tasty
 import Test.Tasty.Runners
@@ -12,6 +12,7 @@
 import qualified Hasql.Query as Query
 import qualified Hasql.Encoders as Encoders
 import qualified Hasql.Decoders as Decoders
+import qualified Hasql.Session as Session
 
 main =
   defaultMain tree
@@ -20,6 +21,28 @@
   localOption (NumThreads 1) $
   testGroup "All tests"
   [
+    testCase "\"another command is already in progress\" bugfix" $
+    let
+      sumQuery :: Query.Query (Int64, Int64) Int64
+      sumQuery =
+        Query.statement sql encoder decoder True
+        where
+          sql =
+            "select ($1 + $2)"
+          encoder =
+            contramap fst (Encoders.value Encoders.int8) <>
+            contramap snd (Encoders.value Encoders.int8)
+          decoder =
+            Decoders.singleRow (Decoders.value Decoders.int8)
+      session :: Session.Session Int64
+      session =
+        do
+          Session.sql "begin;"
+          s <- Session.query (1,1) sumQuery
+          Session.sql "end;"
+          return s
+      in DSL.session session >>= \x -> assertBool (show x) (isRight x)
+    ,
     testCase "Executing the same query twice" $
     pure ()
     ,
@@ -73,6 +96,37 @@
                   Encoders.value (Encoders.interval)
             in DSL.query (10 :: DiffTime) query
       in actualIO >>= \x -> assertEqual (show x) (Right (10 :: DiffTime)) x
+    ,
+    testCase "Unknown" $
+    let
+      actualIO =
+        DSL.session $ do
+          let
+            query =
+              Query.statement sql mempty Decoders.unit True
+              where
+                sql =
+                  "drop type if exists mood"
+            in DSL.query () query
+          let
+            query =
+              Query.statement sql mempty Decoders.unit True
+              where
+                sql =
+                  "create type mood as enum ('sad', 'ok', 'happy')"
+            in DSL.query () query
+          let
+            query =
+              Query.statement sql encoder decoder True
+              where
+                sql =
+                  "select $1 = ('ok' :: mood)"
+                decoder =
+                  (Decoders.singleRow (Decoders.value (Decoders.bool)))
+                encoder =
+                  Encoders.value (Encoders.unknown)
+            in DSL.query "ok" query
+      in actualIO >>= assertEqual "" (Right True)
     ,
     testCase "Enum" $
     let
diff --git a/tasty/Main/DSL.hs b/tasty/Main/DSL.hs
--- a/tasty/Main/DSL.hs
+++ b/tasty/Main/DSL.hs
@@ -1,4 +1,12 @@
-module Main.DSL where
+module Main.DSL
+(
+  Session,
+  SessionError(..),
+  session,
+  Hasql.Session.query,
+  Hasql.Session.sql,
+)
+where
 
 import Main.Prelude
 import qualified Hasql.Connection as HC
@@ -8,17 +16,16 @@
 import qualified Hasql.Session
 
 
-newtype Session a =
-  Session (ReaderT HC.Connection (EitherT Hasql.Session.Error IO) a)
-  deriving (Functor, Applicative, Monad, MonadIO)
+type Session =
+  Hasql.Session.Session
 
 data SessionError =
-  ConnectionError (Maybe ByteString) |
+  ConnectionError (HC.ConnectionError) |
   SessionError (Hasql.Session.Error)
   deriving (Show, Eq)
 
 session :: Session a -> IO (Either SessionError a)
-session (Session impl) =
+session session =
   runEitherT $ acquire >>= \connection -> use connection <* release connection
   where
     acquire =
@@ -33,11 +40,8 @@
             password = ""
             database = "postgres"
     use connection =
-      bimapEitherT SessionError id $
-      runReaderT impl connection
+      EitherT $
+      fmap (mapLeft SessionError) $
+      Hasql.Session.run session connection
     release connection =
       lift $ HC.release connection
-
-query :: a -> HQ.Query a b -> Session b
-query params query =
-  Session $ ReaderT $ \connection -> EitherT $ flip Hasql.Session.run connection $ Hasql.Session.query params query