diff --git a/Debug/FileLocation.hs b/Debug/FileLocation.hs
--- a/Debug/FileLocation.hs
+++ b/Debug/FileLocation.hs
@@ -19,7 +19,7 @@
   [|(\x -> ltrace pre x)|]
 
 -- | TH version  of Debug.Trace.trace that prints a value and a message
--- prefix).
+-- prefix.
 dbgMsg :: String -> Q Exp
 dbgMsg msg = do
   loc <- qLocation
diff --git a/Debug/Util.hs b/Debug/Util.hs
--- a/Debug/Util.hs
+++ b/Debug/Util.hs
@@ -1,7 +1,7 @@
 -- | functions that help you with debugging.
 -- Most would make sense in the Debug.Trace module
 module Debug.Util 
-  (debug, debugM, debugMsg, ltrace, ltraceM, strace, traceId)
+  (debug, debugM, debugMsg, debugMsgIf, ltrace, ltraceM, strace, traceId)
   where
 
 import Debug.Trace (trace)
@@ -16,6 +16,10 @@
 debugMsg :: Show a => String -> a -> a
 debugMsg msg = ltrace ("DEBUG: " ++ msg)
 
+-- | A version of Debug.Trace.trace that just prints a value and a message.
+-- This should be included in Debug.Trace
+debugMsgIf :: Show a => String -> (a -> Bool) -> a -> a
+debugMsgIf msg cond x = if cond x then ltrace ("DEBUG: " ++ msg) x else x
 
 -- | monadic debug - like debug, but works as a standalone line in a monad
 -- TODO: TH version with error loaction info
diff --git a/FileLocation.hs b/FileLocation.hs
--- a/FileLocation.hs
+++ b/FileLocation.hs
@@ -2,7 +2,7 @@
 -- | see Debug.FileLocation module for more definitions
 module FileLocation
   ( err, undef, fromJst, fromRht
-  , debug, debugM, debugMsg, dbg, dbgMsg, trc, ltrace, ltraceM, strace
+  , debug, debugM, debugMsg, debugMsgIf, dbg, dbgMsg, trc, ltrace, ltraceM, strace
   , locationToString
   , thrwIO, thrwsIO
   )
@@ -10,11 +10,9 @@
 
 import FileLocation.LocationString (locationToString)
 import Debug.FileLocation (debug, debugM, debugMsg, dbg, dbgMsg, trc, ltrace, ltraceM, strace)
+import Debug.Util (debugMsgIf)
 import Control.Exception.FileLocation (thrwIO, thrwsIO)
 import Debug.Trace (trace)
--- future plans
--- import Control.Exception.FileLocation (thrw, thrwIO)
-
 import Language.Haskell.TH.Syntax
 
 -- | like Prelude.error, but gives the file location
diff --git a/file-location.cabal b/file-location.cabal
--- a/file-location.cabal
+++ b/file-location.cabal
@@ -1,5 +1,5 @@
 Name:                file-location
-Version:             0.4.1
+Version:             0.4.2
 Synopsis:            common functions that show file location information
 Homepage:            https://github.com/gregwebs/FileLocation.hs
 License:             BSD3