diff --git a/Tools/TimePlot.hs b/Tools/TimePlot.hs
--- a/Tools/TimePlot.hs
+++ b/Tools/TimePlot.hs
@@ -71,22 +71,24 @@
   -- (since given just a Delta t, the compiler won't be able to 
   -- figure out which 't' we're speaking of)
   toSeconds :: Delta t -> t -> Double
+  fromSeconds :: Double -> t -> Delta t
 
 instance HasDelta Double where
   type Delta Double = Double
   add d t = t + d
   sub t2 t1 = t2 - t1
   toSeconds d _ = d
+  fromSeconds d _ = d
 
 instance HasDelta LocalTime where
   type Delta LocalTime = NominalDiffTime
   add d t = utcToLocalTime utc (addUTCTime d (localTimeToUTC utc t))
   sub t2 t1 = diffUTCTime (localTimeToUTC utc t2) (localTimeToUTC utc t1)
   toSeconds d _ = fromIntegral (truncate (1000000*d)) / 1000000
-
+  fromSeconds d _ = fromRational (toRational d)
 
 instance Read NominalDiffTime where
-  readsPrec n s = [(fromIntegral i, s') | (i,s') <- readsPrec n s]
+  readsPrec n s = [(fromSeconds i (undefined::LocalTime), s') | (i,s') <- readsPrec n s]
 
 class (Ord t, HasDelta t, PlotValue t, Show t, Show (Delta t), Read (Delta t)) => TimeAxis t 
 
@@ -137,7 +139,7 @@
                       chartKindF=chartKindF, parseTime=parseTime, fromTime=fromTime, toTime=toTime}
       where
         inFile      = single "input file"  "-if" (error "No input file (-if) specified")
-        outFile     = single "output file" "-o"  (error "No output file (-of) specified")
+        outFile     = single "output file" "-o"  (error "No output file (-o) specified (or have you specified '-of x' and built without --flags=gtk ?)")
         outFormat   = maybe PNG id $ lookup (single "output format" "-of" (name2format outFile)) $
             [("png",PNG), ("pdf",PDF), ("ps",PS), ("svg",SVG)
 #if HAVE_GTK            
diff --git a/timeplot.cabal b/timeplot.cabal
--- a/timeplot.cabal
+++ b/timeplot.cabal
@@ -1,5 +1,5 @@
 Name: timeplot
-Version: 0.2.2
+Version: 0.2.3
 License: BSD3
 License-file: LICENSE
 Copyright: Eugene Kirpichov, 2009