diff --git a/Development/Hake/FunSet.hs b/Development/Hake/FunSet.hs
--- a/Development/Hake/FunSet.hs
+++ b/Development/Hake/FunSet.hs
@@ -11,31 +11,35 @@
 import Data.List                    (isSuffixOf)
 import Data.Function.Tools          (const2)
 import Development.Hake.Types       (Rule, getSrcs)
-import Development.Hake.Tools       (changeSuffix, systemE)
+import Development.Hake.Tools       (changeSuffix, systemE, orDie)
+import Control.Monad.Trans          (MonadIO)
 
+systemExit :: MonadIO m => String -> m ()
+systemExit = flip orDie show . systemE
+
 file :: [String] -> [String] -> (String -> [String] -> [String]) -> Rule
 file trgts srcs cmd
   = ( \f -> or $ map (==f) trgts, const srcs,
-      \t s -> sequence_ $ map systemE $ cmd t s )
+      \t s -> sequence_ $ map systemExit $ cmd t s )
 
 task :: String -> [String] -> Rule
-task trgts cmd = ( (==trgts), const [], const2 $ sequence_ $ map systemE cmd )
+task trgts cmd = ( (==trgts), const [], const2 $ sequence_ $ map systemExit cmd )
 
 rule :: String -> String -> (String -> [String] -> [String]) -> Rule
 rule trgt src cmd
   = ( isSuffixOf trgt, \dst -> [changeSuffix trgt src dst ],
-      \t s -> sequence_ $ map systemE $ cmd t s )
+      \t s -> sequence_ $ map systemExit $ cmd t s )
 
 ruleV ::
   String -> [String] -> [String] -> (String -> [String] -> [String]) -> Rule
 ruleV trgt srcs cmmns cmd
   = ( isSuffixOf trgt, \dst -> map (flip (changeSuffix trgt) dst) srcs ++ cmmns,
-      \t s -> sequence_ $ map systemE $ cmd t s )
+      \t s -> sequence_ $ map systemExit $ cmd t s )
 
 ruleSS ::
   String -> String -> (String -> [String] -> [ (String, [String]) ]) -> Rule
 ruleSS trgt src cmds
   = ( isSuffixOf trgt, \dst -> [ changeSuffix trgt src dst ],
       \t s -> do (srcSrc:_) <- getSrcs $ head s
-	         sequence_ $ map systemE $ snd $ head $
+	         sequence_ $ map systemExit $ snd $ head $
 		   filter ( flip isSuffixOf srcSrc . fst ) $ cmds t s )
diff --git a/Development/Hake/FunSetRaw.hs b/Development/Hake/FunSetRaw.hs
--- a/Development/Hake/FunSetRaw.hs
+++ b/Development/Hake/FunSetRaw.hs
@@ -11,32 +11,36 @@
 import Data.List                    (isSuffixOf)
 import Data.Function.Tools          (const2)
 import Development.Hake.Types       (Rule, getSrcs)
-import Development.Hake.Tools       (changeSuffix, rawSystemE)
+import Development.Hake.Tools       (changeSuffix, rawSystemE, orDie)
+import Control.Monad.Trans          (MonadIO)
 
+rawSystemExit :: MonadIO m => [ String ] -> m ()
+rawSystemExit = flip orDie show . rawSystemE
+
 file :: [String] -> [String] -> (String -> [String] -> [[String]]) -> Rule
 file trgts srcs cmd
   = ( \f -> or $ map (==f) trgts, const srcs,
-      \t s -> sequence_ $ map rawSystemE $ cmd t s )
+      \t s -> sequence_ $ map rawSystemExit $ cmd t s )
 
 task :: String -> [[String]] -> Rule
 task trgts cmd
-  = ( (==trgts), const [], const2 $ sequence_ $ map rawSystemE cmd )
+  = ( (==trgts), const [], const2 $ sequence_ $ map rawSystemExit cmd )
 
 rule :: String -> String -> (String -> [String] -> [[String]]) -> Rule
 rule trgt src cmd
   = ( isSuffixOf trgt, \dst -> [changeSuffix trgt src dst ],
-      \t s -> sequence_ $ map rawSystemE $ cmd t s )
+      \t s -> sequence_ $ map rawSystemExit $ cmd t s )
 
 ruleV ::
   String -> [String] -> [String] -> (String -> [String] -> [[String]]) -> Rule
 ruleV trgt srcs cmmns cmd
   = ( isSuffixOf trgt, \dst -> map (flip (changeSuffix trgt) dst) srcs ++ cmmns,
-      \t s -> sequence_ $ map rawSystemE $ cmd t s )
+      \t s -> sequence_ $ map rawSystemExit $ cmd t s )
 
 ruleSS ::
   String -> String -> (String -> [String] -> [ (String, [[String]]) ]) -> Rule
 ruleSS trgt src cmds
   = ( isSuffixOf trgt, \dst -> [ changeSuffix trgt src dst ],
       \t s -> do (srcSrc:_) <- getSrcs $ head s
-	         sequence_ $ map rawSystemE $ snd $ head $
+	         sequence_ $ map rawSystemExit $ snd $ head $
 		   filter ( flip isSuffixOf srcSrc . fst ) $ cmds t s )
diff --git a/hake.cabal b/hake.cabal
--- a/hake.cabal
+++ b/hake.cabal
@@ -1,5 +1,5 @@
 Name:		hake
-Version:	1.1
+Version:	1.2
 License:	GPL
 License-file:	LICENSE
 Author:		Yoshikuni Jujo