diff --git a/Debug/Trace/LocationTH.hs b/Debug/Trace/LocationTH.hs
--- a/Debug/Trace/LocationTH.hs
+++ b/Debug/Trace/LocationTH.hs
@@ -20,6 +20,8 @@
     , undef
     , check
     , checkIO
+    , checkTrace
+    , checkTraceIO
     ) where
 
 import qualified Control.Exception as C
@@ -76,13 +78,12 @@
 assert :: Q Exp -> Q Exp
 assert t = do
     st <- pprint `fmap` t
-    [| if' (not $t) $ throw $ AssertionFailed $
-        $__LOCATION__ ++ ": Assertion `" ++ st ++ "' failed"
-     |]
+    [| assert' $t $__LOCATION__ st |]
 
-if' :: Bool -> a -> a -> a
-if' True  x _ = x
-if' False _ y = y
+assert' :: Bool -> String -> String -> a -> a
+assert' False loc st _ = throw $ AssertionFailed $
+    loc ++ ": Assertion `" ++ st ++ "' failed"
+assert' True  _   _  x = x
 
 --
 -- | A location-emitting 'error' call.
@@ -93,8 +94,11 @@
 -- *** Exception: <interactive>:1:1-8: no such thing.
 --
 failure :: Q Exp
-failure = [| error . ($__LOCATION__ ++) . (": " ++) |]
+failure = [| failure' $__LOCATION__ |]
 
+failure' :: String -> String -> a
+failure' loc t = error $ loc ++ ": " ++ t
+
 --
 -- | A location-emitting 'undefined'.
 --
@@ -141,7 +145,40 @@
 -- "*** Exception: <interactive>:1:1-8: /foo: openFile: does not exist (No such file or directory)
 --
 checkIO :: Q Exp
-checkIO = [| flip C.catch (return . $failure . showEx) |]
+checkIO = [| checkIO' $__LOCATION__ |]
+
+checkIO' :: String -> IO a -> IO a
+checkIO' loc a = C.catch a $ \e -> return $ failure' loc (showEx e)
+
+--
+-- | 'checkTrace' extends 'check' with the ability to add a custom string
+-- to the error message.
+--
+-- @$checkTrace :: String -> c -> c@
+--
+-- >>> $checkTrace "XXX" $ head []
+-- *** Exception: <interactive>:1:1-6 XXX: Prelude.head: empty list
+--
+checkTrace :: Q Exp
+checkTrace = [| checkTrace' $__LOCATION__ |]
+
+checkTrace' :: String -> String -> a -> a
+checkTrace' loc t = unsafePerformIO . checkTraceIO' loc t . C.evaluate
+
+--
+-- | 'checkTraceIO' extends 'checkIO' with the ability to add a custom
+-- string to the error message.
+--
+-- @$checkTraceIO :: String -> IO a -> IO a@
+--
+-- >>> $checkTraceIO "XXX" $ readFile "/foo"
+-- "*** Exception: <interactive>:1:1-8 XXX: /foo: openFile: does not exist (No such file or directory)
+--
+checkTraceIO :: Q Exp
+checkTraceIO = [| checkTraceIO' $__LOCATION__ |]
+
+checkTraceIO' :: String -> String -> IO a -> IO a
+checkTraceIO' loc t = checkIO' (loc ++ " " ++ t)
 
 showEx :: C.SomeException -> String
 showEx = show
diff --git a/loch-th.cabal b/loch-th.cabal
--- a/loch-th.cabal
+++ b/loch-th.cabal
@@ -1,5 +1,5 @@
 Name:                loch-th
-Version:             0.2
+Version:             0.2.1
 Synopsis:            Support for precise error locations in source files (Template Haskell version)
 Description:         This module provides a Template Haskell based mechanism to
 		     tag failures with the location of the failure call. The
@@ -12,8 +12,8 @@
 Maintainer:          tomi@nomi.cz
 Category:            Development
 Build-type:          Simple
-Cabal-version:       >=1.2
+Cabal-version:       >=1.6
 
 Library
   Exposed-modules:     Debug.Trace.LocationTH
-  Build-depends:       base >=4 && <5, template-haskell, pretty
+  Build-depends:       base == 4.*, template-haskell, pretty