diff --git a/regex-genex.cabal b/regex-genex.cabal
--- a/regex-genex.cabal
+++ b/regex-genex.cabal
@@ -1,5 +1,5 @@
 Name            : regex-genex
-Version         : 0.3.1
+Version         : 0.3.2
 license         : OtherLicense
 license-file    : LICENSE
 cabal-version   : >= 1.6
@@ -20,14 +20,14 @@
     other-modules:    Regex.Genex.Pure
     extensions      : ImplicitParams, NamedFieldPuns, ParallelListComp, PatternGuards, RecordWildCards
     build-depends:
-        base >= 3 && < 5, haskell98, mtl, containers, sbv, regex-tdfa, stream-monad, text, logict
+        base >= 3 && < 5, mtl, containers, sbv >= 0.9.22, regex-tdfa, stream-monad, text, logict
 
 executable genex
     main-is:            Main.hs
     hs-source-dirs:     . src
     extensions      : ImplicitParams, NamedFieldPuns, ParallelListComp, PatternGuards, RecordWildCards
     build-depends:
-        base >= 3 && < 5, haskell98, mtl, containers, sbv, regex-tdfa
+        base >= 3 && < 5, mtl, containers, sbv, regex-tdfa
 
 source-repository head
   type:     git
diff --git a/src/Regex/Genex.hs b/src/Regex/Genex.hs
--- a/src/Regex/Genex.hs
+++ b/src/Regex/Genex.hs
@@ -138,8 +138,8 @@
 
 exactMatch :: (?pats :: [(Pattern, GroupLens)]) => Len -> Symbolic SBool
 exactMatch len = do
-    str <- mkFreeVars $ fromEnum len
-    initialFlips <- mkFreeVars 1
+    str <- mkExistVars $ fromEnum len
+    initialFlips <- mkExistVars 1
     captureAt <- newArray_ (Just minBound)
     captureLen <- newArray_ (Just minBound)
     let ?str = str
@@ -346,10 +346,10 @@
              (isWordCharAt (pos-1) <+> isWordCharAt pos)
 
 
-displayString :: [SMTResult] -> Hits -> (Hits -> IO ()) -> IO ()
+displayString :: [SatResult] -> Hits -> (Hits -> IO ()) -> IO ()
 displayString [] a next = next a
 displayString (r:rs) a next = do
-    let (chars, rank) = getModel r
+    let Right (chars, rank) = getModel r
     putStr $ show (length (chars :: [Word8])) ++ "."
     let n = show (rank :: Word64)
     putStr (replicate (8 - length n) '0')
@@ -361,7 +361,7 @@
     where
     chr = Data.Char.chr . fromEnum
 
-genexWith :: Monoid a => ([SMTResult] -> Hits -> (Hits -> IO a) -> IO a) -> [[Char]] -> IO a
+genexWith :: Monoid a => ([SatResult] -> Hits -> (Hits -> IO a) -> IO a) -> [[Char]] -> IO a
 genexWith f regexes = do
     let ?grp = mempty
     let p'lens = [ ((p', groupLens), lens)
@@ -377,20 +377,20 @@
     Monoid a => ResultHandler a -> [Len] -> Hits -> IO a
 tryWith _ [] _ = return mempty
 tryWith f (len:lens) acc = if len > maxLength then return mempty else do
-    AllSatResult allRes <- allSat $ exactMatch len
-    f allRes acc $ tryWith f lens
+    AllSatResult (_, allRes) <- allSat $ exactMatch len
+    f (map SatResult allRes) acc $ tryWith f lens
 
-type ResultHandler a = [SMTResult] -> Hits -> (Hits -> IO a) -> IO a
+type ResultHandler a = [SatResult] -> Hits -> (Hits -> IO a) -> IO a
 
-getStringWith :: (Model -> a) -> [SMTResult] -> Hits -> (Hits -> IO [a]) -> IO [a]
+getStringWith :: (Model -> a) -> [SatResult] -> Hits -> (Hits -> IO [a]) -> IO [a]
 getStringWith _ [] a next = next a
 getStringWith f (r:rs) a next = do
-    let (chars, rank) = getModel r
+    let Right (chars, rank) = getModel r
     rest <- if (a+1 >= maxHits) then return [] else
         unsafeInterleaveIO $ getStringWith f rs (a+1) next
     return (f (Model chars rank):rest)
 
-getString :: [SMTResult] -> Hits -> (Hits -> IO [String]) -> IO [String]
+getString :: [SatResult] -> Hits -> (Hits -> IO [String]) -> IO [String]
 getString = getStringWith $ \Model{ modelChars } -> map chr modelChars
     where
     chr = Data.Char.chr . fromEnum
diff --git a/src/Regex/Genex/Pure.hs b/src/Regex/Genex/Pure.hs
--- a/src/Regex/Genex/Pure.hs
+++ b/src/Regex/Genex/Pure.hs
@@ -29,6 +29,7 @@
 
 run :: Pattern -> Stream T.Text
 run p = case p of
+    PEmpty -> pure T.empty
     PChar{..} -> isChar getPatternChar
     PAny {getPatternSet = PatternSet (Just cset) _ _ _} -> each $ map T.singleton $ Set.toList cset
     PQuest p -> pure T.empty <|> run p