diff --git a/liquid-fixpoint.cabal b/liquid-fixpoint.cabal
--- a/liquid-fixpoint.cabal
+++ b/liquid-fixpoint.cabal
@@ -1,5 +1,5 @@
 name:                liquid-fixpoint
-version:             0.5.0.0
+version:             0.5.0.1
 Copyright:           2010-15 Ranjit Jhala, University of California, San Diego.
 synopsis:            Predicate Abstraction-based Horn-Clause/Implication Constraint Solver
 homepage:            https://github.com/ucsd-progsys/liquid-fixpoint
@@ -29,15 +29,24 @@
 
 Extra-Source-Files: tests/neg/*.fq
                   , tests/pos/*.fq
+                  , unix/Language/Fixpoint/Utils/*.hs
+                  , win/Language/Fixpoint/Utils/*.hs
 
 Source-Repository head
   Type:        git
   Location:    https://github.com/ucsd-progsys/liquid-fixpoint/
 
+Flag devel
+  Description: turn on stricter error reporting for development
+  Default:     False
+  Manual:      True
+
 Executable fixpoint
   default-language: Haskell98
   Main-is:       Fixpoint.hs
   ghc-options:   -threaded -W -fno-warn-missing-methods
+  if flag(devel)
+    ghc-options: -Werror
   hs-source-dirs: bin
   Build-Depends: base >= 4.7 && < 5
                , liquid-fixpoint
@@ -45,6 +54,8 @@
 Library
   default-language: Haskell98
   ghc-options:     -W -fno-warn-missing-methods
+  if flag(devel)
+    ghc-options:   -Werror
   hs-source-dirs:  src
   Exposed-Modules: Language.Fixpoint.Types.Names,
                    Language.Fixpoint.Types.Errors,
@@ -123,6 +134,7 @@
     Build-Depends: located-base
   if !os(windows)
     Build-Depends: ascii-progress >= 0.3
+    hs-source-dirs: unix
   if os(windows)
     hs-source-dirs: win
 
@@ -130,7 +142,9 @@
   default-language: Haskell98
   type:             exitcode-stdio-1.0
   hs-source-dirs:   tests
-  ghc-options:      -O2 -threaded
+  ghc-options:      -threaded
+  if flag(devel)
+    ghc-options:    -Werror
   main-is:          test.hs
   build-depends:    base,
                     directory,
diff --git a/src/Language/Fixpoint/Utils/Progress.hs b/src/Language/Fixpoint/Utils/Progress.hs
deleted file mode 100644
--- a/src/Language/Fixpoint/Utils/Progress.hs
+++ /dev/null
@@ -1,55 +0,0 @@
--- | Progress Bar API
-module Language.Fixpoint.Utils.Progress (
-      withProgress
-    , progressInit
-    , progressTick
-    , progressClose
-    ) where
-
-import           Control.Monad                    (unless)
-import           System.IO.Unsafe                 (unsafePerformIO)
-import           System.Console.CmdArgs.Verbosity (isLoud)
-import           Data.IORef
-
-
-import           System.Console.AsciiProgress
-
-{-# NOINLINE pbRef #-}
-pbRef :: IORef (Maybe ProgressBar)
-pbRef = unsafePerformIO (newIORef Nothing)
-
-withProgress :: Int -> IO a -> IO a
-withProgress n act = displayConsoleRegions $ do
-  -- putStrLn $ "withProgress: " ++ show n
-  progressInit n
-  r <- act
-  progressClose
-  return r
-
-progressInit :: Int -> IO ()
-progressInit n = do
-  loud <- isLoud
-  unless loud $ do
-    pr <- mkPB n
-    writeIORef pbRef (Just pr)
-
-mkPB   :: Int -> IO ProgressBar
-
-mkPB n = newProgressBar def { pgWidth       = 80
-                            , pgTotal       = toInteger n
-                            , pgFormat      = "Working :percent [:bar]"
-                            , pgPendingChar = '.'
-                            , pgOnCompletion = Just "Done solving." --  :percent."
-                            }
-
-progressTick :: IO ()
-progressTick    = go =<< readIORef pbRef
-  where
-   go (Just pr) = tick pr
-   go _         = return ()
-
-progressClose :: IO ()
-progressClose = go =<< readIORef pbRef
-  where
-    go (Just p) = complete p
-    go _        = return ()
diff --git a/unix/Language/Fixpoint/Utils/Progress.hs b/unix/Language/Fixpoint/Utils/Progress.hs
new file mode 100644
--- /dev/null
+++ b/unix/Language/Fixpoint/Utils/Progress.hs
@@ -0,0 +1,55 @@
+-- | Progress Bar API
+module Language.Fixpoint.Utils.Progress (
+      withProgress
+    , progressInit
+    , progressTick
+    , progressClose
+    ) where
+
+import           Control.Monad                    (unless)
+import           System.IO.Unsafe                 (unsafePerformIO)
+import           System.Console.CmdArgs.Verbosity (isLoud)
+import           Data.IORef
+
+
+import           System.Console.AsciiProgress
+
+{-# NOINLINE pbRef #-}
+pbRef :: IORef (Maybe ProgressBar)
+pbRef = unsafePerformIO (newIORef Nothing)
+
+withProgress :: Int -> IO a -> IO a
+withProgress n act = displayConsoleRegions $ do
+  -- putStrLn $ "withProgress: " ++ show n
+  progressInit n
+  r <- act
+  progressClose
+  return r
+
+progressInit :: Int -> IO ()
+progressInit n = do
+  loud <- isLoud
+  unless loud $ do
+    pr <- mkPB n
+    writeIORef pbRef (Just pr)
+
+mkPB   :: Int -> IO ProgressBar
+
+mkPB n = newProgressBar def { pgWidth       = 80
+                            , pgTotal       = toInteger n
+                            , pgFormat      = "Working :percent [:bar]"
+                            , pgPendingChar = '.'
+                            , pgOnCompletion = Just "Done solving." --  :percent."
+                            }
+
+progressTick :: IO ()
+progressTick    = go =<< readIORef pbRef
+  where
+   go (Just pr) = tick pr
+   go _         = return ()
+
+progressClose :: IO ()
+progressClose = go =<< readIORef pbRef
+  where
+    go (Just p) = complete p
+    go _        = return ()
diff --git a/win/Language/Fixpoint/Utils/Progress.hs b/win/Language/Fixpoint/Utils/Progress.hs
new file mode 100644
--- /dev/null
+++ b/win/Language/Fixpoint/Utils/Progress.hs
@@ -0,0 +1,19 @@
+-- | Progress Bar API
+module Language.Fixpoint.Utils.Progress (
+      withProgress
+    , progressInit
+    , progressTick
+    , progressClose
+    ) where
+
+withProgress :: Int -> IO a -> IO a
+withProgress _ x = x
+
+progressInit :: Int -> IO ()
+progressInit _ = return ()
+
+progressTick :: IO ()
+progressTick = return ()
+
+progressClose :: IO ()
+progressClose = return ()