diff --git a/bumper.cabal b/bumper.cabal
--- a/bumper.cabal
+++ b/bumper.cabal
@@ -1,5 +1,5 @@
 Name:             bumper
-Version:          0.5.0.1
+Version:          0.5.0.2
 Synopsis:         Automatically bump package versions, also transitively.
 Description:      Automatically bump package versions, also transitively.
 Author:           Silk
diff --git a/src/Bumper.hs b/src/Bumper.hs
--- a/src/Bumper.hs
+++ b/src/Bumper.hs
@@ -1,8 +1,10 @@
 module Main where
 
 import Config
+import Control.Monad
 import Data.Label
 import Data.List
+import Data.Maybe
 import Data.Version
 import Distribution.Package hiding (Package)
 import Distribution.Text
@@ -30,6 +32,12 @@
 run conf act =
   do -- Load packages
      ps   <- packages
+
+     --Check for non-existent packages
+     let changePks = map fst (get setVersion conf) ++ concat (M.elems (get bump conf))
+         notFound = filter (not . isJust . flip lookupPackage ps) changePks
+     when (not $ null notFound) $ putStrLn $ "[Warning] packages not found: " ++ (intercalate "," $ map display notFound)
+
      -- Retrieve base versions
      base <- maybe (return ps) (flip getBaseVersions ps) $ get global conf
      let changed = (if get transitive conf then trans base else id)
diff --git a/src/Package.hs b/src/Package.hs
--- a/src/Package.hs
+++ b/src/Package.hs
@@ -92,9 +92,9 @@
 modifyDependency :: Dependency -> String -> String
 modifyDependency (Dependency nm range) s = subRegex (mkRegexWithOpts regex False False) s result
   where regex = "(build-depends" ++ whiteReg ++ ":" ++ "[^:]*"
-              ++ "[ ,\n\t]" ++ display nm ++ whiteReg ++ ")[, ]([" ++ rangeChar ++ " \t\n]*[" ++ rangeChar ++ "])"
+              ++ "[ ,\n\t]" ++ display nm ++ whiteReg ++ ")([" ++ rangeChar ++ " \t\n]*[" ++ rangeChar ++ "])"
         rangeChar = "0-9.*&|()<>="
-        result = "\\1 " ++ printRange range
+        result = "\\1" ++ printRange range
 
 -- | Data structure containing package modifications
 type PackageChanges = (Maybe Version, [Dependency])