diff --git a/selda-postgresql.cabal b/selda-postgresql.cabal
--- a/selda-postgresql.cabal
+++ b/selda-postgresql.cabal
@@ -1,5 +1,5 @@
 name:                selda-postgresql
-version:             0.1.5.0
+version:             0.1.5.1
 synopsis:            PostgreSQL backend for the Selda database EDSL.
 description:         PostgreSQL backend for the Selda database EDSL.
                      Requires the PostgreSQL @libpq@ development libraries to be
@@ -28,14 +28,14 @@
     OverloadedStrings
     CPP
   build-depends:
-      base             >=4.8     && <5
-    , exceptions       >=0.8     && <0.9
-    , selda            >=0.1.8.0 && <0.2
-    , text             >=1.0     && <1.3
+      base       >=4.8     && <5
+    , bytestring >=0.9 && <0.11
+    , exceptions >=0.8     && <0.9
+    , selda      >=0.1.8.0 && <0.2
+    , text       >=1.0     && <1.3
   if !flag(haste)
     build-depends:
-        bytestring       >=0.9 && <0.11
-      , postgresql-libpq >=0.9 && <0.10
+      postgresql-libpq >=0.9 && <0.10
   if impl(ghc < 7.11)
     build-depends:
       transformers  >=0.4 && <0.6
diff --git a/src/Database/Selda/PostgreSQL.hs b/src/Database/Selda/PostgreSQL.hs
--- a/src/Database/Selda/PostgreSQL.hs
+++ b/src/Database/Selda/PostgreSQL.hs
@@ -6,6 +6,7 @@
   , pgOpen, seldaClose
   , pgConnString
   ) where
+import qualified Data.ByteString.Char8 as BS
 import Data.Dynamic
 import Data.Monoid
 import qualified Data.Text as T
@@ -17,7 +18,6 @@
 #ifndef __HASTE__
 import Database.Selda.PostgreSQL.Encoding
 import Database.PostgreSQL.LibPQ hiding (user, pass, db, host)
-import qualified Data.ByteString.Char8 as BS
 #endif
 
 -- | PostgreSQL connection information.
@@ -63,6 +63,26 @@
   }
 infixl 4 `auth`
 
+-- | Convert `PGConnectInfo` into `ByteString`
+pgConnString :: PGConnectInfo -> BS.ByteString
+#ifdef __HASTE__
+pgConnString PGConnectInfo{..} = error "pgConnString called in JS context"
+#else
+pgConnString PGConnectInfo{..} = mconcat
+  [ "host=", encodeUtf8 pgHost, " "
+  , "port=", BS.pack (show pgPort), " "
+  , "dbname=", encodeUtf8 pgDatabase, " "
+  , case pgUsername of
+      Just user -> "user=" <> encodeUtf8 user <> " "
+      _         -> ""
+  , case pgPassword of
+      Just pass -> "password=" <> encodeUtf8 pass <> " "
+      _         -> ""
+  , "connect_timeout=10", " "
+  , "client_encoding=UTF8"
+  ]
+#endif
+
 -- | Perform the given computation over a PostgreSQL database.
 --   The database connection is guaranteed to be closed when the computation
 --   terminates.
@@ -74,11 +94,15 @@
 withPostgreSQL ci m = do
   c <- pgOpen ci
   runSeldaT m c `finally` seldaClose c
+#endif
 
 -- | Open a new PostgreSQL connection. The connection will persist across
 --   calls to 'runSeldaT', and must be explicitly closed using 'seldaClose'
 --   when no longer needed.
 pgOpen :: (MonadIO m, MonadThrow m) => PGConnectInfo -> m SeldaConnection
+#ifdef __HASTE__
+pgOpen _ = return $ error "pgOpen called in JS context"
+#else
 pgOpen ci = do
   conn <- liftIO $ connectdb connstr
   st <- liftIO $ status conn
@@ -116,22 +140,6 @@
     left _        = error "impossible"
     right (Right x) = x
     right _         = error "impossible"
-
--- | Convert `PGConnectInfo` into `ByteString`
-pgConnString :: PGConnectInfo -> BS.ByteString
-pgConnString PGConnectInfo{..} = mconcat
-  [ "host=", encodeUtf8 pgHost, " "
-  , "port=", BS.pack (show pgPort), " "
-  , "dbname=", encodeUtf8 pgDatabase, " "
-  , case pgUsername of
-      Just user -> "user=" <> encodeUtf8 user <> " "
-      _         -> ""
-  , case pgPassword of
-      Just pass -> "password=" <> encodeUtf8 pass <> " "
-      _         -> ""
-  , "connect_timeout=10", " "
-  , "client_encoding=UTF8"
-  ]
 
 pgQueryRunner :: Connection -> Bool -> T.Text -> [Param] -> IO (Either Int (Int, [[SqlValue]]))
 pgQueryRunner c return_lastid q ps = do
diff --git a/src/Database/Selda/PostgreSQL/Encoding.hs b/src/Database/Selda/PostgreSQL/Encoding.hs
--- a/src/Database/Selda/PostgreSQL/Encoding.hs
+++ b/src/Database/Selda/PostgreSQL/Encoding.hs
@@ -1,9 +1,19 @@
-{-# LANGUAGE GADTs, BangPatterns, OverloadedStrings #-}
+{-# LANGUAGE GADTs, BangPatterns, OverloadedStrings, CPP #-}
 -- | Encoding/decoding for PostgreSQL.
 module Database.Selda.PostgreSQL.Encoding
   ( toSqlValue, fromSqlValue, fromSqlType
   , readInt
   ) where
+#ifdef __HASTE__
+
+toSqlValue, fromSqlValue, fromSqlType, readInt :: a
+toSqlValue = undefined
+fromSqlValue = undefined
+fromSqlType = undefined
+readInt = undefined
+
+#else
+
 import Control.Exception (throw)
 import qualified Data.ByteString as BS
 import Data.ByteString.Builder
@@ -112,3 +122,4 @@
   case LBS.toChunks bs of
     [bs'] -> bs'
     bss   -> BS.concat bss
+#endif