diff --git a/README.md b/README.md
--- a/README.md
+++ b/README.md
@@ -3,6 +3,8 @@
 hocilib is a FFI binding of [ocilib](http://www.ocilib.net) for haskell.
 
 [![build status](https://travis-ci.org/fpinsight/hocilib.svg?branch=master)](https://travis-ci.org/fpinsight/hocilib)
+[![hocilib on Stackage LTS](http://stackage.org/package/hocilib/badge/lts)](http://stackage.org/lts/package/hocilib)
+[![hocilib on Stackage Nightly](http://stackage.org/package/hocilib/badge/nightly)](http://stackage.org/nightly/package/hocilib)
 
 # Join in!
 
diff --git a/hocilib.cabal b/hocilib.cabal
--- a/hocilib.cabal
+++ b/hocilib.cabal
@@ -1,5 +1,5 @@
 name:               hocilib
-version:            0.1.0
+version:            0.2.0
 license:            BSD3
 license-file:       LICENSE
 category:           Database, Oracle, Ocilib, FFI
@@ -64,9 +64,10 @@
   extra-libraries:  ocilib
   extra-lib-dirs:   /usr/local/lib
 
-  build-depends: base             >= 4.8 && < 5
-               , containers       >= 0.5 && < 1
-               , inline-c         >= 0.5 && < 1
+  build-depends: base             >= 4.8  && < 5
+               , bytestring       >= 0.10 && < 0.11
+               , containers       >= 0.5  && < 1
+               , inline-c         >= 0.5  && < 1
                , template-haskell
 
 
diff --git a/src/Database/Ocilib/Bindings.hs b/src/Database/Ocilib/Bindings.hs
--- a/src/Database/Ocilib/Bindings.hs
+++ b/src/Database/Ocilib/Bindings.hs
@@ -84,6 +84,7 @@
     , ociBindSetCharsetForm
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
 import           Foreign.C.String
@@ -121,20 +122,20 @@
     fmap toBool [C.exp| int { OCI_IsRebindingAllowed($(OCI_Statement *st)) } |]
 
 -- | Bind a boolean variable (PL/SQL ONLY)
-ociBindBoolean :: Ptr OCI_Statement -> String -> Ptr CInt -> IO Bool
-ociBindBoolean st n d = withCString n (\n' ->
+ociBindBoolean :: Ptr OCI_Statement -> ByteString -> Ptr CInt -> IO Bool
+ociBindBoolean st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindBoolean($(OCI_Statement *st), $(const char *n'), $(int *d)) } |]
     )
 
 -- | Bind an short variable.
-ociBindShort :: Ptr OCI_Statement -> String -> Ptr CShort -> IO Bool
-ociBindShort st n d = withCString n (\n' ->
+ociBindShort :: Ptr OCI_Statement -> ByteString -> Ptr CShort -> IO Bool
+ociBindShort st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindShort($(OCI_Statement *st), $(const char *n'), $(short *d)) } |]
     )
 
 -- | Bind an array of shorts.
-ociBindArrayOfShorts :: Ptr OCI_Statement -> String -> Ptr CShort -> CUInt -> IO Bool
-ociBindArrayOfShorts st n d nb = withCString n (\n' ->
+ociBindArrayOfShorts :: Ptr OCI_Statement -> ByteString -> Ptr CShort -> CUInt -> IO Bool
+ociBindArrayOfShorts st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfShorts($(OCI_Statement *st)
                                                       , $(const char *n')
                                                       , $(short *d)
@@ -142,16 +143,16 @@
     )
 
 -- | Bind an unsigned short variable.
-ociBindUnsignedShort :: Ptr OCI_Statement -> String -> Ptr CUShort -> IO Bool
-ociBindUnsignedShort st n d = withCString n (\n' ->
+ociBindUnsignedShort :: Ptr OCI_Statement -> ByteString -> Ptr CUShort -> IO Bool
+ociBindUnsignedShort st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindUnsignedShort($(OCI_Statement *st)
                                                       , $(const char *n')
                                                       , $(unsigned short *d)) } |]
     )
 
 -- | Bind an array of unsigned shorts.
-ociBindArrayOfUnsignedShorts :: Ptr OCI_Statement -> String -> Ptr CUShort -> CUInt -> IO Bool
-ociBindArrayOfUnsignedShorts st n d nb = withCString n (\n' ->
+ociBindArrayOfUnsignedShorts :: Ptr OCI_Statement -> ByteString -> Ptr CUShort -> CUInt -> IO Bool
+ociBindArrayOfUnsignedShorts st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfUnsignedShorts($(OCI_Statement * st)
                                                               , $(const char *n')
                                                               , $(unsigned short *d)
@@ -159,16 +160,16 @@
     )
 
 -- | Bind an integer variable.
-ociBindInt :: Ptr OCI_Statement -> String -> Ptr CInt -> IO Bool
-ociBindInt st n d = withCString n (\n' ->
+ociBindInt :: Ptr OCI_Statement -> ByteString -> Ptr CInt -> IO Bool
+ociBindInt st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindInt($(OCI_Statement *st)
                                             , $(const char *n')
                                             , $(int *d)) } |]
     )
 
 -- | Bind an array of integers.
-ociBindArrayOfInts :: Ptr OCI_Statement -> String -> Ptr CInt -> CUInt -> IO Bool
-ociBindArrayOfInts st n d nb = withCString n (\n' ->
+ociBindArrayOfInts :: Ptr OCI_Statement -> ByteString -> Ptr CInt -> CUInt -> IO Bool
+ociBindArrayOfInts st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfInts($(OCI_Statement *st)
                                                     , $(const char *n')
                                                     , $(int *d)
@@ -176,16 +177,16 @@
     )
 
 -- | Bind an unsigned integer variable.
-ociBindUnsignedInt :: Ptr OCI_Statement -> String -> Ptr CUInt -> IO Bool
-ociBindUnsignedInt st n d = withCString n (\n' ->
+ociBindUnsignedInt :: Ptr OCI_Statement -> ByteString -> Ptr CUInt -> IO Bool
+ociBindUnsignedInt st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindUnsignedInt($(OCI_Statement *st)
                                                     , $(const char* n')
                                                     , $(unsigned int *d)) } |]
     )
 
 -- | Bind an array of unsigned integers.
-ociBindArrayOfUnsignedInts :: Ptr OCI_Statement -> String -> Ptr CUInt -> CUInt -> IO Bool
-ociBindArrayOfUnsignedInts st n d nb = withCString n (\n' ->
+ociBindArrayOfUnsignedInts :: Ptr OCI_Statement -> ByteString -> Ptr CUInt -> CUInt -> IO Bool
+ociBindArrayOfUnsignedInts st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfUnsignedInts($(OCI_Statement *st)
                                                             , $(const char *n')
                                                             , $(unsigned int *d)
@@ -194,8 +195,8 @@
 {-
 -- | Bind a big integer variable.
 -- boolean OCI_BindBigInt (OCI_Statement *stmt, const otext *name, big_int *data)
-ociBindBigInt :: Ptr OCI_Statement -> String -> Ptr Big_Int -> IO Bool
-ociBindBigInt st n d = withCString n (\n' ->
+ociBindBigInt :: Ptr OCI_Statement -> ByteString -> Ptr Big_Int -> IO Bool
+ociBindBigInt st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindBigInt($(OCI_Statement *st)
                                                , $(const char *n')
                                                , $(Big_Int  *d)) } |]
@@ -212,9 +213,9 @@
 -}
 
 -- | Bind a string variable.
-ociBindString :: Ptr OCI_Statement -> String -> CString -> CUInt -> IO Bool
+ociBindString :: Ptr OCI_Statement -> ByteString -> CString -> CUInt -> IO Bool
 ociBindString st name d l =
-    withCString name (\n ->
+    useAsCString name (\n ->
         fmap toBool [C.exp| int { OCI_BindString($(OCI_Statement *st)
                                                , $(char *n)
                                                , $(char *d)
@@ -222,9 +223,9 @@
     )
 
 -- | Bind an array of strings.
-ociBindArrayOfStrings :: Ptr OCI_Statement -> String -> CString -> CUInt -> CUInt -> IO Bool
+ociBindArrayOfStrings :: Ptr OCI_Statement -> ByteString -> CString -> CUInt -> CUInt -> IO Bool
 ociBindArrayOfStrings st name d len nbElem =
-    withCString name (\n ->
+    useAsCString name (\n ->
         fmap toBool [C.exp| int { OCI_BindArrayOfStrings($(OCI_Statement *st)
                                                        , $(char *n)
                                                        , $(char *d)
@@ -240,16 +241,16 @@
 -- boolean OCI_BindArrayOfRaws (OCI_Statement *stmt, const otext *name, void *data, unsigned int len, unsigned int nbelem)
 
 -- | Bind a double variable.
-ociBindDouble :: Ptr OCI_Statement -> String -> Ptr CDouble -> IO Bool
-ociBindDouble st n d = withCString n (\n' ->
+ociBindDouble :: Ptr OCI_Statement -> ByteString -> Ptr CDouble -> IO Bool
+ociBindDouble st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindDouble($(OCI_Statement *st)
                                                , $(const char *n')
                                                , $(double *d)) } |]
     )
 
 -- | Bind an array of doubles.
-ociBindArrayOfDoubles :: Ptr OCI_Statement -> String -> Ptr CDouble -> CUInt -> IO Bool
-ociBindArrayOfDoubles st n d nb = withCString n (\n' ->
+ociBindArrayOfDoubles :: Ptr OCI_Statement -> ByteString -> Ptr CDouble -> CUInt -> IO Bool
+ociBindArrayOfDoubles st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfDoubles($(OCI_Statement *st)
                                                        , $(const char *n')
                                                        , $(double *d)
@@ -257,23 +258,23 @@
     )
 
 -- | Bind a float variable.
-ociBindFloat :: Ptr OCI_Statement -> String -> Ptr CFloat -> IO Bool
-ociBindFloat st n d = withCString n (\n' ->
+ociBindFloat :: Ptr OCI_Statement -> ByteString -> Ptr CFloat -> IO Bool
+ociBindFloat st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindFloat($(OCI_Statement *st)
                                               , $(const char *n')
                                               , $(float *d)) } |]
     )
 -- | Bind an array of floats.
-ociBindArrayOfFloats :: Ptr OCI_Statement -> String -> Ptr CFloat -> CUInt -> IO Bool
-ociBindArrayOfFloats st n d nb = withCString n (\n' ->
+ociBindArrayOfFloats :: Ptr OCI_Statement -> ByteString -> Ptr CFloat -> CUInt -> IO Bool
+ociBindArrayOfFloats st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfFloats($(OCI_Statement *st)
                                                       , $(const char *n')
                                                       , $(float *d)
                                                       , $(unsigned int nb)) } |]
     )
 -- | Bind a date variable.
-ociBindDate :: Ptr OCI_Statement -> String -> Ptr OCI_Date -> IO Bool
-ociBindDate st n d = withCString n (\n' ->
+ociBindDate :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Date -> IO Bool
+ociBindDate st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindDate($(OCI_Statement *st)
                                              , $(const char* n')
                                              , $(OCI_Date *d)) } |]
@@ -282,8 +283,8 @@
 -- | Bind an array of dates.
 -- boolean OCI_BindArrayOfDates (OCI_Statement *stmt, const otext *name, OCI_Date **data, unsigned int nbelem)
 {-
-ociBindArrayOfDates :: Ptr OCI_Statement -> String -> Ptr OCI_Date -> CUInt -> IO Bool
-ociBindArrayOfDates st n d nb = withCString n (\n' ->
+ociBindArrayOfDates :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Date -> CUInt -> IO Bool
+ociBindArrayOfDates st n d nb = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindArrayOfDates($(OCI_Statement *st)
                                                      , $(const char *n')
                                                      , $(OCI_Date *d)
@@ -292,8 +293,8 @@
 -}
 
 -- | Bind a timestamp variable.
-ociBindTimestamp :: Ptr OCI_Statement -> String -> Ptr OCI_Timestamp -> IO Bool
-ociBindTimestamp st n d = withCString n (\n' ->
+ociBindTimestamp :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Timestamp -> IO Bool
+ociBindTimestamp st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindTimestamp($(OCI_Statement *st)
                                                   , $(const char *n')
                                                   , $(OCI_Timestamp *d)) } |]
@@ -303,8 +304,8 @@
 -- boolean OCI_BindArrayOfTimestamps (OCI_Statement *stmt, const otext *name, OCI_Timestamp **data, unsigned int type, unsigned int nbelem)
 
 -- | Bind an interval variable.
-ociBindInterval :: Ptr OCI_Statement -> String -> Ptr OCI_Interval -> IO Bool
-ociBindInterval st n d = withCString n (\n' ->
+ociBindInterval :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Interval -> IO Bool
+ociBindInterval st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindInterval($(OCI_Statement *st)
                                                  , $(const char *n')
                                                  , $(OCI_Interval *d)) } |]
@@ -313,8 +314,8 @@
 -- boolean OCI_BindArrayOfIntervals (OCI_Statement *stmt, const otext *name, OCI_Interval **data, unsigned int type, unsigned int nbelem)
 
 -- | Bind a Lob variable.
-ociBindLob :: Ptr OCI_Statement -> String -> Ptr OCI_Lob -> IO Bool
-ociBindLob st n d = withCString n (\n' ->
+ociBindLob :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Lob -> IO Bool
+ociBindLob st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindLob($(OCI_Statement *st)
                                             , $(const char *n')
                                             , $(OCI_Lob *d)) } |]
@@ -324,8 +325,8 @@
 -- boolean OCI_BindArrayOfLobs (OCI_Statement *stmt, const otext *name, OCI_Lob **data, unsigned int type, unsigned int nbelem)
 
 -- | Bind a File variable.
-ociBindFile :: Ptr OCI_Statement -> String -> Ptr OCI_File -> IO Bool
-ociBindFile st n d = withCString n (\n' ->
+ociBindFile :: Ptr OCI_Statement -> ByteString -> Ptr OCI_File -> IO Bool
+ociBindFile st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindFile($(OCI_Statement *st)
                                              , $(const char *n')
                                              , $(OCI_File *d)) } |]
@@ -344,8 +345,8 @@
 -- boolean OCI_BindArrayOfObjects (OCI_Statement *stmt, const otext *name, OCI_Object **data, OCI_TypeInfo *typinf, unsigned int nbelem)
 
 -- | Bind a Collection variable.
-ociBindColl :: Ptr OCI_Statement -> String -> Ptr OCI_Coll -> IO Bool
-ociBindColl st n d = withCString n (\n' ->
+ociBindColl :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Coll -> IO Bool
+ociBindColl st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindColl($(OCI_Statement *st)
                                              , $(const char *n')
                                              , $(OCI_Coll *d)) } |]
@@ -355,8 +356,8 @@
 -- boolean OCI_BindArrayOfColls (OCI_Statement *stmt, const otext *name, OCI_Coll **data, OCI_TypeInfo *typinf, unsigned int nbelem)
 
 -- | Bind a Ref variable.
-ociBindRef :: Ptr OCI_Statement -> String -> Ptr OCI_Ref -> IO Bool
-ociBindRef st n d = withCString n (\n' ->
+ociBindRef :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Ref -> IO Bool
+ociBindRef st n d = useAsCString n (\n' ->
         fmap toBool [C.exp| int { OCI_BindRef($(OCI_Statement *st)
                                             , $(const char *n')
                                             , $(OCI_Ref *d)) } |]
@@ -366,14 +367,14 @@
 -- boolean OCI_BindArrayOfRefs (OCI_Statement *stmt, const otext *name, OCI_Ref **data, OCI_TypeInfo *typinf, unsigned int nbelem)
 
 -- | Bind a Statement variable (PL/SQL Ref Cursor)
-ociBindStatement :: Ptr OCI_Statement -> String -> Ptr OCI_Statement -> IO Bool
-ociBindStatement st name d = withCString name (\name' ->
+ociBindStatement :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Statement -> IO Bool
+ociBindStatement st name d = useAsCString name (\name' ->
         fmap toBool [C.exp| int { OCI_BindStatement($(OCI_Statement *st), $(const char *name'), $(OCI_Statement *d)) } |]
     )
 
 -- | Bind a Long variable.
-ociBindLong :: Ptr OCI_Statement -> String -> Ptr OCI_Long -> CUInt -> IO Bool
-ociBindLong st name d s = withCString name (\name' ->
+ociBindLong :: Ptr OCI_Statement -> ByteString -> Ptr OCI_Long -> CUInt -> IO Bool
+ociBindLong st name d s = useAsCString name (\name' ->
         fmap toBool [C.exp| int { OCI_BindLong($(OCI_Statement *st), $(const char *name'), $(OCI_Long *d), $(unsigned int s)) } |]
     )
 
@@ -394,22 +395,22 @@
 ociGetBind st i = fmap toMaybePtr [C.exp| OCI_Bind* { OCI_GetBind($(OCI_Statement *st), $(unsigned int i)) } |]
 
 -- | Return a bind handle from its name.
-ociGetBind2 :: Ptr OCI_Statement -> String -> IO (Maybe (Ptr OCI_Bind))
-ociGetBind2 st name = withCString name (\name' ->
+ociGetBind2 :: Ptr OCI_Statement -> ByteString -> IO (Maybe (Ptr OCI_Bind))
+ociGetBind2 st name = useAsCString name (\name' ->
         fmap toMaybePtr [C.exp| OCI_Bind* { OCI_GetBind2($(OCI_Statement *st), $(char *name')) } |]
     )
 
 -- | Return the index of the bind from its name belonging to the given statement.
-ociGetBindIndex :: Ptr OCI_Statement -> String -> IO CUInt
-ociGetBindIndex st name = withCString name (\name' ->
+ociGetBindIndex :: Ptr OCI_Statement -> ByteString -> IO CUInt
+ociGetBindIndex st name = useAsCString name (\name' ->
         [C.exp| unsigned int { OCI_GetBindIndex($(OCI_Statement *st), $(char* name')) } |]
     )
 
 -- | Return the name of the given bind.
-ociBindGetName :: Ptr OCI_Bind -> IO String
+ociBindGetName :: Ptr OCI_Bind -> IO ByteString
 ociBindGetName b = do
     name <- [C.exp| const char* { OCI_BindGetName($(OCI_Bind *b)) } |]
-    peekCString name
+    packCString name
 
 -- | Set the direction mode of a bind handle.
 ociBindSetDirection :: Ptr OCI_Bind -> BindDirectionMode -> IO Bool
diff --git a/src/Database/Ocilib/BitMask.hs b/src/Database/Ocilib/BitMask.hs
--- a/src/Database/Ocilib/BitMask.hs
+++ b/src/Database/Ocilib/BitMask.hs
@@ -1,4 +1,5 @@
 {-# LANGUAGE DefaultSignatures #-}
+{-# OPTIONS_HADDOCK hide, prune, ignore-exports #-}
 
 -- |
 -- Module:      Database.Ocilib.BitMask
diff --git a/src/Database/Ocilib/Collections.hs b/src/Database/Ocilib/Collections.hs
--- a/src/Database/Ocilib/Collections.hs
+++ b/src/Database/Ocilib/Collections.hs
@@ -79,6 +79,7 @@
     , ociElemSetNull
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
 import           Foreign.C.String
@@ -230,10 +231,10 @@
 -}
 
 -- | Return the String value of the given collection element.
-ociElemGetString :: Ptr OCI_Elem -> IO String
+ociElemGetString :: Ptr OCI_Elem -> IO ByteString
 ociElemGetString elem = do
     s <- [C.exp| const char* { OCI_ElemGetString($(OCI_Elem *elem)) } |]
-    peekCString s
+    packCString s
 
 {-
 -- | Read the RAW value of the collection element into the given buffer.
@@ -295,9 +296,9 @@
 -}
 
 -- | Set a string value to a collection element.
-ociElemSetString :: Ptr OCI_Elem -> String -> IO Bool
+ociElemSetString :: Ptr OCI_Elem -> ByteString -> IO Bool
 ociElemSetString elem value =
-    withCString value (\value' ->
+    useAsCString value (\value' ->
         fmap toBool [C.exp| int { OCI_ElemSetString($(OCI_Elem *elem), $(char *value')) } |]
     )
 {-
diff --git a/src/Database/Ocilib/Connection.hs b/src/Database/Ocilib/Connection.hs
--- a/src/Database/Ocilib/Connection.hs
+++ b/src/Database/Ocilib/Connection.hs
@@ -23,9 +23,8 @@
     , ociBreak
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
--- import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
@@ -42,12 +41,12 @@
 type Connection = Ptr OCI_Connection
 
 -- | Create a physical connection to an Oracle database server.
-ociConnectionCreate :: String -> String -> String -> SessionMode -> IO (Maybe Connection)
+ociConnectionCreate :: ByteString -> ByteString -> ByteString -> SessionMode -> IO (Maybe Connection)
 ociConnectionCreate db user pass mode = do
     let m = fromIntegral $ fromEnum mode
-    withCString db ( \d ->
-        withCString user ( \u ->
-            withCString pass ( \p ->
+    useAsCString db ( \d ->
+        useAsCString user ( \u ->
+            useAsCString pass ( \p ->
                 fmap toMaybePtr [C.exp| OCI_Connection* { OCI_ConnectionCreate($(char* d), $(char* u), $(char* p), $(unsigned int m)) } |]
             )
         )
diff --git a/src/Database/Ocilib/Errors.hs b/src/Database/Ocilib/Errors.hs
--- a/src/Database/Ocilib/Errors.hs
+++ b/src/Database/Ocilib/Errors.hs
@@ -24,9 +24,9 @@
     , ociErrorGetRow
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
 import           Database.Ocilib.Oci
@@ -44,10 +44,10 @@
 ociGetLastError = fmap toMaybePtr [C.exp| OCI_Error* { OCI_GetLastError() } |]
 
 -- | Retrieve error message from error handle.
-ociErrorGetString :: Ptr OCI_Error -> IO String
+ociErrorGetString :: Ptr OCI_Error -> IO ByteString
 ociErrorGetString err = do
     s <- [C.exp| const char* { OCI_ErrorGetString($(OCI_Error *err)) } |]
-    peekCString s
+    packCString s
 
 -- | Retrieve the type of error from error handle.
 ociErrorGetType :: Ptr OCI_Error -> IO ErrorType
diff --git a/src/Database/Ocilib/Fetch.hs b/src/Database/Ocilib/Fetch.hs
--- a/src/Database/Ocilib/Fetch.hs
+++ b/src/Database/Ocilib/Fetch.hs
@@ -89,9 +89,9 @@
     , ociGetDataLength
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
@@ -152,24 +152,24 @@
 ociGetColumn rs i = [C.exp| OCI_Column* { OCI_GetColumn($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the column object handle from its name in the resultset.
-ociGetColumn2 :: Ptr OCI_Resultset -> String -> IO (Ptr OCI_Column)
+ociGetColumn2 :: Ptr OCI_Resultset -> ByteString -> IO (Ptr OCI_Column)
 ociGetColumn2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| OCI_Column* { OCI_GetColumn2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
 -- | Return the index of the column in the result from its name.
-ociGetColumnIndex :: Ptr OCI_Resultset -> String -> IO CUInt
+ociGetColumnIndex :: Ptr OCI_Resultset -> ByteString -> IO CUInt
 ociGetColumnIndex rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| unsigned int { OCI_GetColumnIndex($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
 -- | Return the name of the given column.
-ociColumnGetName :: Ptr OCI_Column -> IO String
+ociColumnGetName :: Ptr OCI_Column -> IO ByteString
 ociColumnGetName c = do
     s <- [C.exp| const char* { OCI_ColumnGetName($(OCI_Column *c)) } |]
-    peekCString s
+    packCString s
 
 -- | Return the type of the given column.
 ociColumnGetType :: Ptr OCI_Column -> IO ColumnType
@@ -183,10 +183,10 @@
 -}
 
 -- | Return the Oracle SQL type name of the column data type.
-ociColumnGetSQLType :: Ptr OCI_Column -> IO String
+ociColumnGetSQLType :: Ptr OCI_Column -> IO ByteString
 ociColumnGetSQLType c = do
     s <- [C.exp| const char* { OCI_ColumnGetSQLType($(OCI_Column *c)) } |]
-    peekCString s
+    packCString s
 
 {-
 -- | Return the Oracle SQL Full name including precision and size of the column data type.
@@ -238,9 +238,9 @@
 ociSetStructNumericType rs i t = fmap toBool [C.exp| int { OCI_SetStructNumericType($(OCI_Resultset *rs), $(unsigned int i), $(unsigned int t)) } |]
 
 -- | set the numeric data type of the given structure member (identified from column name in the resultset) to retrieve when calling OCI_GetStruct()
-ociSetStructNumericType2 :: Ptr OCI_Resultset -> String -> CUInt -> IO Bool -- FIXME use enum for the type
+ociSetStructNumericType2 :: Ptr OCI_Resultset -> ByteString -> CUInt -> IO Bool -- FIXME use enum for the type
 ociSetStructNumericType2 rs name t =
-    withCString name (\n ->
+    useAsCString name (\n ->
         fmap toBool [C.exp| int { OCI_SetStructNumericType2($(OCI_Resultset *rs), $(char *n), $(unsigned int t))} |]
     )
 
@@ -254,9 +254,9 @@
 ociGetShort rs i = [C.exp| short { OCI_GetShort($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current short value of the column from its name in the resultset.
-ociGetShort2 :: Ptr OCI_Resultset -> String -> IO CShort
+ociGetShort2 :: Ptr OCI_Resultset -> ByteString -> IO CShort
 ociGetShort2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| short { OCI_GetShort2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -265,9 +265,9 @@
 ociGetUnsignedShort rs i = [C.exp| unsigned short { OCI_GetUnsignedShort($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current unsigned short value of the column from its name in the resultset.
-ociGetUnsignedShort2 :: Ptr OCI_Resultset -> String -> IO CUShort
+ociGetUnsignedShort2 :: Ptr OCI_Resultset -> ByteString -> IO CUShort
 ociGetUnsignedShort2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| unsigned short { OCI_GetUnsignedShort2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -276,9 +276,9 @@
 ociGetInt rs i = [C.exp| int { OCI_GetInt($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current integer value of the column from its name in the resultset.
-ociGetInt2 :: Ptr OCI_Resultset -> String -> IO CInt
+ociGetInt2 :: Ptr OCI_Resultset -> ByteString -> IO CInt
 ociGetInt2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| int { OCI_GetInt2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -287,9 +287,9 @@
 ociGetUnsignedInt rs i = [C.exp| unsigned int { OCI_GetUnsignedInt($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current unsigned integer value of the column from its name in the resultset.
-ociGetUnsignedInt2 :: Ptr OCI_Resultset -> String -> IO CUInt
+ociGetUnsignedInt2 :: Ptr OCI_Resultset -> ByteString -> IO CUInt
 ociGetUnsignedInt2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| unsigned int { OCI_GetUnsignedInt2($(OCI_Resultset *rs), $(char *n))} |]
     )
 
@@ -309,17 +309,17 @@
 -}
 
 -- | Return the current string value of the column at the given index in the resultset.
-ociGetString :: Ptr OCI_Resultset -> CUInt -> IO String
+ociGetString :: Ptr OCI_Resultset -> CUInt -> IO ByteString
 ociGetString rs i = do
     s <- [C.exp| const char* { OCI_GetString($(OCI_Resultset *rs), $(unsigned int i)) }|]
-    peekCString s -- FIXME release CString ?
+    packCString s -- FIXME release CString ?
 
 -- | Return the current string value of the column from its name in the resultset.
-ociGetString2 :: Ptr OCI_Resultset -> String -> IO String
+ociGetString2 :: Ptr OCI_Resultset -> ByteString -> IO ByteString
 ociGetString2 rs name =
-    withCString name (\n -> do
+    useAsCString name (\n -> do
         s <- [C.exp| const char* { OCI_GetString2($(OCI_Resultset *rs), $(char *n)) } |]
-        peekCString s
+        packCString s
     )
 
 {-
@@ -335,9 +335,9 @@
 ociGetDouble rs i = [C.exp| double { OCI_GetDouble($(OCI_Resultset *rs), $(unsigned int i))} |]
 
 -- | Return the current double value of the column from its name in the resultset.
-ociGetDouble2 :: Ptr OCI_Resultset -> String -> IO CDouble
+ociGetDouble2 :: Ptr OCI_Resultset -> ByteString -> IO CDouble
 ociGetDouble2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| double { OCI_GetDouble2($(OCI_Resultset *rs), $(char *n))} |]
     )
 
@@ -346,9 +346,9 @@
 ociGetFloat rs i = [C.exp| float { OCI_GetFloat($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current float value of the column from its name in the resultset.
-ociGetFloat2 :: Ptr OCI_Resultset -> String -> IO CFloat
+ociGetFloat2 :: Ptr OCI_Resultset -> ByteString -> IO CFloat
 ociGetFloat2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| float { OCI_GetFloat2($(OCI_Resultset *rs), $(char *n))} |]
     )
 
@@ -357,9 +357,9 @@
 ociGetDate rs i = [C.exp| OCI_Date* { OCI_GetDate($(OCI_Resultset *rs), $(unsigned int i))} |]
 
 -- | Return the current date value of the column from its name in the resultset.
-ociGetDate2 :: Ptr OCI_Resultset -> String -> IO (Ptr OCI_Date)
+ociGetDate2 :: Ptr OCI_Resultset -> ByteString -> IO (Ptr OCI_Date)
 ociGetDate2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| OCI_Date* { OCI_GetDate2($(OCI_Resultset *rs), $(char *n))} |]
     )
 
@@ -368,9 +368,9 @@
 ociGetTimestamp rs i = [C.exp| OCI_Timestamp* { OCI_GetTimestamp($(OCI_Resultset *rs), $(unsigned int i)) } |]
 
 -- | Return the current timestamp value of the column from its name in the resultset.
-ociGetTimestamp2 :: Ptr OCI_Resultset -> String -> IO (Ptr OCI_Timestamp)
+ociGetTimestamp2 :: Ptr OCI_Resultset -> ByteString -> IO (Ptr OCI_Timestamp)
 ociGetTimestamp2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| OCI_Timestamp* { OCI_GetTimestamp2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -379,9 +379,9 @@
 ociGetInterval rs i = [C.exp| OCI_Interval* { OCI_GetInterval($(OCI_Resultset *rs), $(unsigned int i))  } |]
 
 -- | Return the current interval value of the column from its name in the resultset.
-ociGetInterval2 :: Ptr OCI_Resultset -> String -> IO (Ptr OCI_Interval)
+ociGetInterval2 :: Ptr OCI_Resultset -> ByteString -> IO (Ptr OCI_Interval)
 ociGetInterval2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| OCI_Interval* { OCI_GetInterval2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -390,9 +390,9 @@
 ociGetStatement rs i = [C.exp| OCI_Statement* { OCI_GetStatement($(OCI_Resultset *rs), $(unsigned int i)) }|]
 
 -- | Return the current cursor value of the column from its name in the resultset.
-ociGetStatement2 :: Ptr OCI_Resultset -> String -> IO (Ptr OCI_Statement)
+ociGetStatement2 :: Ptr OCI_Resultset -> ByteString -> IO (Ptr OCI_Statement)
 ociGetStatement2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         [C.exp| OCI_Statement* { OCI_GetStatement2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
@@ -441,9 +441,9 @@
 
 -- | Check if the current row value is null for the column of the given name in the resultset.
 -- boolean OCI_IsNull2 (OCI_Resultset *rs, const otext *name)
-ociIsNull2 :: Ptr OCI_Resultset -> String -> IO Bool
+ociIsNull2 :: Ptr OCI_Resultset -> ByteString -> IO Bool
 ociIsNull2 rs name =
-    withCString name (\n ->
+    useAsCString name (\n ->
         fmap toBool [C.exp| int { OCI_IsNull2($(OCI_Resultset *rs), $(char *n)) } |]
     )
 
diff --git a/src/Database/Ocilib/Internal.hs b/src/Database/Ocilib/Internal.hs
--- a/src/Database/Ocilib/Internal.hs
+++ b/src/Database/Ocilib/Internal.hs
@@ -13,6 +13,7 @@
 
 import Foreign.Ptr
 
+-- | return Nothing if nullPtr Ptr otherwise
 toMaybePtr :: Ptr a -> Maybe (Ptr a)
 toMaybePtr a
     | a == nullPtr = Nothing
diff --git a/src/Database/Ocilib/Pool.hs b/src/Database/Ocilib/Pool.hs
--- a/src/Database/Ocilib/Pool.hs
+++ b/src/Database/Ocilib/Pool.hs
@@ -33,9 +33,9 @@
     , ociPoolSetStatementCacheSize
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
@@ -52,13 +52,13 @@
 type Pool = Ptr OCI_Pool
 
 -- | Create an Oracle pool of connections or sessions.
-ociPoolCreate :: String -> String -> String -> PoolType -> SessionMode -> CUInt -> CUInt -> CUInt -> IO (Maybe Pool)
+ociPoolCreate :: ByteString -> ByteString -> ByteString -> PoolType -> SessionMode -> CUInt -> CUInt -> CUInt -> IO (Maybe Pool)
 ociPoolCreate db user pwd pType mode minCon maxCon incrCon = do
     let pt = fromIntegral $ fromEnum pType
         m  = fromIntegral $ fromEnum mode
-    withCString db (\d ->
-        withCString user (\u ->
-            withCString pwd (\p ->
+    useAsCString db (\d ->
+        useAsCString user (\u ->
+            useAsCString pwd (\p ->
                 fmap toMaybePtr [C.exp| OCI_Pool* { OCI_PoolCreate( $(char *d)
                                                                   , $(char *u)
                                                                   , $(char *p)
@@ -76,9 +76,9 @@
 ociPoolFree p = fmap toBool [C.exp| int { OCI_PoolFree($(OCI_Pool *p))} |]
 
 -- | Get a connection from the pool.
-ociPoolGetConnection :: Ptr OCI_Pool -> String -> IO (Maybe (Ptr OCI_Connection))
+ociPoolGetConnection :: Ptr OCI_Pool -> ByteString -> IO (Maybe (Ptr OCI_Connection))
 ociPoolGetConnection p tag =
-    withCString tag (\t ->
+    useAsCString tag (\t ->
         fmap toMaybePtr [C.exp| OCI_Connection* { OCI_PoolGetConnection($(OCI_Pool *p), $(char *t)) } |]
     )
 
diff --git a/src/Database/Ocilib/Schemas.hs b/src/Database/Ocilib/Schemas.hs
--- a/src/Database/Ocilib/Schemas.hs
+++ b/src/Database/Ocilib/Schemas.hs
@@ -15,9 +15,9 @@
 
 module Database.Ocilib.Schemas where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
@@ -32,10 +32,10 @@
 -- Describing Schema Meta data and Objects
 
 -- | Retrieve the available type info information.
-ociTypeInfoGet :: Ptr OCI_Connection -> String -> TypeInfoType -> IO (Maybe (Ptr OCI_TypeInfo))
+ociTypeInfoGet :: Ptr OCI_Connection -> ByteString -> TypeInfoType -> IO (Maybe (Ptr OCI_TypeInfo))
 ociTypeInfoGet c name typ = do
     let typ' = fromIntegral $ fromEnum typ
-    withCString name (\name' ->
+    useAsCString name (\name' ->
             fmap toMaybePtr [C.exp| OCI_TypeInfo* { OCI_TypeInfoGet($(OCI_Connection *c), $(char *name'), $(unsigned int typ')) } |]
         )
 
@@ -60,7 +60,7 @@
 ociTypeInfoGetColumn t i = [C.exp| OCI_Column* { OCI_TypeInfoGetColumn($(OCI_TypeInfo *t), $(unsigned int i))} |]
 
 -- | Return the name described by the type info object.
-ociTypeInfoGetName :: Ptr OCI_TypeInfo -> IO String
+ociTypeInfoGetName :: Ptr OCI_TypeInfo -> IO ByteString
 ociTypeInfoGetName t = do
     s <- [C.exp| const char* { OCI_TypeInfoGetName($(OCI_TypeInfo *t)) } |]
-    peekCString s
+    packCString s
diff --git a/src/Database/Ocilib/Statement.hs b/src/Database/Ocilib/Statement.hs
--- a/src/Database/Ocilib/Statement.hs
+++ b/src/Database/Ocilib/Statement.hs
@@ -46,9 +46,9 @@
     , ociStatementGetConnection
     ) where
 
+import           Data.ByteString
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
-import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
@@ -71,9 +71,9 @@
 ociStatementFree s = fmap toBool [C.exp| int { OCI_StatementFree($(OCI_Statement *s)) } |]
 
 -- | Prepare a SQL statement or PL/SQL block.
-ociPrepare :: Ptr OCI_Statement -> String -> IO Bool
+ociPrepare :: Ptr OCI_Statement -> ByteString -> IO Bool
 ociPrepare s sql =
-    withCString sql (\q ->
+    useAsCString sql (\q ->
         fmap toBool [C.exp| int { OCI_Prepare($(OCI_Statement *s), $(char *q)) } |]
     )
 
@@ -82,31 +82,31 @@
 ociExecute s = fmap toBool [C.exp| int { OCI_Execute($(OCI_Statement *s)) } |]
 
 -- | Prepare and Execute a SQL statement or PL/SQL block.
-ociExecuteStmt :: Ptr OCI_Statement -> String -> IO Bool
+ociExecuteStmt :: Ptr OCI_Statement -> ByteString -> IO Bool
 ociExecuteStmt s sql =
-    withCString sql (\q ->
+    useAsCString sql (\q ->
         fmap toBool [C.exp| int { OCI_ExecuteStmt($(OCI_Statement *s), $(char *q)) } |]
     )
 
 -- | Parse a SQL statement or PL/SQL block.
-ociParse :: Ptr OCI_Statement -> String -> IO Bool
+ociParse :: Ptr OCI_Statement -> ByteString -> IO Bool
 ociParse st sql =
-    withCString sql (\s ->
+    useAsCString sql (\s ->
         fmap toBool [C.exp| int { OCI_Parse($(OCI_Statement *st), $(char *s)) } |]
     )
 
 -- | Describe the select list of a SQL select statement.
-ociDescribe :: Ptr OCI_Statement -> String -> IO Bool
+ociDescribe :: Ptr OCI_Statement -> ByteString -> IO Bool
 ociDescribe st sql =
-    withCString sql (\s ->
+    useAsCString sql (\s ->
         fmap toBool [C.exp| int {OCI_Describe($(OCI_Statement *st), $(char *s)) } |]
     )
 
 -- | Return the last SQL or PL/SQL statement prepared or executed by the statement.
-ociGetSql :: Ptr OCI_Statement -> IO String
+ociGetSql :: Ptr OCI_Statement -> IO ByteString
 ociGetSql st = do
     r <- [C.exp| const char* { OCI_GetSql($(OCI_Statement *st)) } |] -- FIXME should release the CString
-    peekCString r
+    packCString r
 
 -- | Return the error position (in terms of characters) in the SQL statement where the error occurred in case of SQL parsing error.
 ociGetSqlErrorPos :: Ptr OCI_Statement -> IO CUInt
@@ -121,10 +121,10 @@
 ociGetSQLCommand st = [C.exp| unsigned int { OCI_GetSQLCommand($(OCI_Statement *st)) } |]
 
 -- | Return the verb of the SQL command held by the statement handle.
-ociGetSQLVerb :: Ptr OCI_Statement -> IO String
+ociGetSQLVerb :: Ptr OCI_Statement -> IO ByteString
 ociGetSQLVerb st = do
     v <- [C.exp| const char* { OCI_GetSQLVerb($(OCI_Statement *st)) } |]
-    peekCString v
+    packCString v
 
 -- Statement Control
 
diff --git a/src/Database/Ocilib/Timestamp.hs b/src/Database/Ocilib/Timestamp.hs
--- a/src/Database/Ocilib/Timestamp.hs
+++ b/src/Database/Ocilib/Timestamp.hs
@@ -17,7 +17,6 @@
 
 import           Data.Monoid ((<>))
 import           Foreign.C.Types
--- import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
diff --git a/src/Database/Ocilib/Transaction.hs b/src/Database/Ocilib/Transaction.hs
--- a/src/Database/Ocilib/Transaction.hs
+++ b/src/Database/Ocilib/Transaction.hs
@@ -16,13 +16,10 @@
 module Database.Ocilib.Transaction where
 
 import           Data.Monoid ((<>))
--- import           Foreign.C.Types
--- import           Foreign.C.String
 import           Foreign.Marshal.Utils
 import           Foreign.Ptr
 import qualified Language.C.Inline as C
 import           Database.Ocilib.Oci
--- import           Database.Ocilib.Enums
 
 C.context (C.baseCtx <> C.funCtx <> ociCtx)
 
diff --git a/stack.yaml b/stack.yaml
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-6.13
+resolver: lts-7.2
 packages:
 - '.'
 extra-deps: []