diff --git a/Setup.hs b/Setup.hs
--- a/Setup.hs
+++ b/Setup.hs
@@ -6,6 +6,6 @@
 main = do putStrLn msg
           defaultMain
 
-msg = "regex-pcre needs to compile against the libpcre libary from http://www.pcre.org/\n\
+msg = "\nregex-pcre needs to compile against the libpcre libary from http://www.pcre.org/\n\
       \You might also need to edit the end of the regex-pcre.cabal file to point at\n\
       \the directories where libpcre 'include' and 'lib' have been installed.\n"
diff --git a/Text/Regex/PCRE.hs b/Text/Regex/PCRE.hs
--- a/Text/Regex/PCRE.hs
+++ b/Text/Regex/PCRE.hs
@@ -65,6 +65,6 @@
 
 getVersion_Text_Regex_PCRE :: Version
 getVersion_Text_Regex_PCRE =
-  Version { versionBranch = [0,92]
+  Version { versionBranch = [0,93]
           , versionTags = ["unstable"]
           }
diff --git a/Text/Regex/PCRE/ByteString.hs b/Text/Regex/PCRE/ByteString.hs
--- a/Text/Regex/PCRE/ByteString.hs
+++ b/Text/Regex/PCRE/ByteString.hs
@@ -48,12 +48,13 @@
 import Text.Regex.PCRE.Wrap -- all
 import Data.Array(Array,listArray)
 import Data.ByteString(ByteString)
-import qualified Data.ByteString as B(empty,useAsCString,last,take,drop,null)
+import qualified Data.ByteString as B(empty,useAsCString,last,take,drop,null,pack)
 import qualified Data.ByteString.Base as B(unsafeUseAsCString,unsafeUseAsCStringLen)
 import System.IO.Unsafe(unsafePerformIO)
 import Text.Regex.Base.RegexLike(RegexContext(..),RegexMaker(..),RegexLike(..),MatchOffset,MatchLength)
 import Text.Regex.Base.Impl(polymatch,polymatchM)
 import Foreign.C.String(CStringLen)
+import Foreign(nullPtr)
 
 instance RegexContext Regex ByteString ByteString where
   match = polymatch
@@ -63,8 +64,13 @@
 unwrap x = case x of Left err -> fail ("Text.Regex.PCRE.ByteString died: "++ show err)
                      Right v -> return v
 
+{-# INLINE asCStringLen #-}
 asCStringLen :: ByteString -> (CStringLen -> IO a) -> IO a
-asCStringLen = B.unsafeUseAsCStringLen
+asCStringLen s op = B.unsafeUseAsCStringLen s checked
+  where checked cs@(ptr,_) | ptr == nullPtr = B.unsafeUseAsCStringLen myEmpty (op . trim)
+                           | otherwise = op cs
+        myEmpty = B.pack [0]
+        trim (ptr,_) = (ptr,0)
 
 instance RegexMaker Regex CompOption ExecOption ByteString where
   makeRegexOpts c e pattern = unsafePerformIO $
@@ -77,9 +83,9 @@
     asCStringLen bs (wrapTest 0 regex) >>= unwrap
   matchOnce regex bs = unsafePerformIO $
     execute regex bs >>= unwrap
-  matchAll regex bs = unsafePerformIO $ 
+  matchAll regex bs = unsafePerformIO $
     asCStringLen bs (wrapMatchAll regex) >>= unwrap
-  matchCount regex bs = unsafePerformIO $ 
+  matchCount regex bs = unsafePerformIO $
     asCStringLen bs (wrapCount regex) >>= unwrap
 
 -- ---------------------------------------------------------------------
@@ -111,7 +117,7 @@
   maybeStartEnd <- asCStringLen bs (wrapMatch 0 regex)
   case maybeStartEnd of
     Right Nothing -> return (Right Nothing)
-    Right (Just parts) -> 
+    Right (Just parts) ->
       return . Right . Just . listArray (0,pred (length parts))
       . map (\(s,e)->(fromIntegral s, fromIntegral (e-s))) $ parts
     Left err -> return (Left err)
@@ -123,7 +129,7 @@
   let getSub (start,stop) | start == unusedOffset = B.empty
                           | otherwise = B.take (stop-start) . B.drop start $ bs
       matchedParts [] = (B.empty,B.empty,bs,[]) -- no information
-      matchedParts (matchedStartStop@(start,stop):subStartStop) = 
+      matchedParts (matchedStartStop@(start,stop):subStartStop) =
         (B.take start bs
         ,getSub matchedStartStop
         ,B.drop stop bs
diff --git a/Text/Regex/PCRE/ByteString/Lazy.hs b/Text/Regex/PCRE/ByteString/Lazy.hs
--- a/Text/Regex/PCRE/ByteString/Lazy.hs
+++ b/Text/Regex/PCRE/ByteString/Lazy.hs
@@ -48,13 +48,14 @@
 import Text.Regex.PCRE.Wrap -- all
 import Data.Array(Array)
 import qualified Data.ByteString.Lazy as L(ByteString,toChunks,fromChunks,last,null,snoc)
-import qualified Data.ByteString as B(ByteString,concat)
+import qualified Data.ByteString as B(ByteString,concat,pack)
 import qualified Data.ByteString.Base as B(unsafeUseAsCString,unsafeUseAsCStringLen)
 import System.IO.Unsafe(unsafePerformIO)
 import Text.Regex.Base.RegexLike(RegexContext(..),RegexMaker(..),RegexLike(..),MatchOffset,MatchLength)
 import Text.Regex.Base.Impl(polymatch,polymatchM)
 import qualified Text.Regex.PCRE.ByteString as BS(execute,regexec)
 import Foreign.C.String(CString,CStringLen)
+import Foreign(nullPtr)
 
 instance RegexContext Regex L.ByteString L.ByteString where
   match = polymatch
@@ -80,7 +81,11 @@
 
 {-# INLINE asCStringLen #-}
 asCStringLen :: L.ByteString -> (CStringLen -> IO a) -> IO a
-asCStringLen s = B.unsafeUseAsCStringLen (fromLazy s)
+asCStringLen ls op = B.unsafeUseAsCStringLen (fromLazy ls) checked
+  where checked cs@(ptr,_) | ptr == nullPtr = B.unsafeUseAsCStringLen myEmpty (op . trim)
+                           | otherwise = op cs
+        myEmpty = B.pack [0]
+        trim (ptr,_) = (ptr,0)
 
 instance RegexMaker Regex CompOption ExecOption L.ByteString where
   makeRegexOpts c e pattern = unsafePerformIO $
@@ -93,9 +98,9 @@
     asCStringLen bs (wrapTest 0 regex) >>= unwrap
   matchOnce regex bs = unsafePerformIO $
     execute regex bs >>= unwrap
-  matchAll regex bs = unsafePerformIO $ 
+  matchAll regex bs = unsafePerformIO $
     asCStringLen bs (wrapMatchAll regex) >>= unwrap
-  matchCount regex bs = unsafePerformIO $ 
+  matchCount regex bs = unsafePerformIO $
     asCStringLen bs (wrapCount regex) >>= unwrap
 
 -- ---------------------------------------------------------------------
diff --git a/regex-pcre.cabal b/regex-pcre.cabal
--- a/regex-pcre.cabal
+++ b/regex-pcre.cabal
@@ -1,5 +1,5 @@
 Name:                   regex-pcre
-Version:                0.92
+Version:                0.93
 -- Cabal-Version:       >=1.1.4
 License:                BSD3
 License-File:           LICENSE
@@ -30,7 +30,7 @@
 -- GHC-Options:            -Wall -Werror
 GHC-Options:            -Wall -Werror -O2
 -- GHC-Options:            -Wall -ddump-minimal-imports
--- GHC-Prof-Options: 
+-- GHC-Prof-Options:
 -- Hugs-Options:
 -- NHC-Options:
 -- C-Sources:
@@ -39,5 +39,5 @@
 -- Frameworks:
 CC-Options:             -DHAVE_PCRE_H
 Extra-Libraries:        pcre
--- Include-Dirs:           /opt/local/include
--- Extra-Lib-Dirs:         /opt/local/lib
+--Include-Dirs:           /opt/local/include
+--Extra-Lib-Dirs:         /opt/local/lib