diff --git a/CHANGELOG.md b/CHANGELOG.md
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,9 @@
 # Revision history for viewprof
 
+## 0.0.0.13 - 2018-01-22
+
+* Relax upper version bound for brick
+
 ## 0.0.0.12 - 2017-12-12
 
 * Relax upper version bound for vty
diff --git a/bin/viewprof.hs b/bin/viewprof.hs
--- a/bin/viewprof.hs
+++ b/bin/viewprof.hs
@@ -12,9 +12,11 @@
 import Control.Monad
 import Data.Foldable
 import Data.Function (on)
-import Data.List.NonEmpty
+import Data.List.NonEmpty hiding (head, length)
 import Data.Maybe
+import System.Directory (doesFileExist)
 import System.Environment
+import System.Exit (exitFailure)
 import Text.Printf
 import qualified Data.List.NonEmpty as NE
 
@@ -71,10 +73,33 @@
   | ModulesCache !Int
   deriving (Eq, Ord, Show)
 
+data Args = Args
+  { profilePath :: FilePath
+  }
+
+usage :: IO a
+usage = do
+  pn <- getProgName
+  putStrLn $ "Usage: " ++ pn ++ " <file.prof>"
+  exitFailure
+
+parseArgs :: IO Args
+parseArgs = do
+  args <- getArgs
+  case args of
+    [arg] -> validateArgs (Args arg)
+    _ -> usage
+  where
+    validateArgs :: Args -> IO Args
+    validateArgs args = do
+      b <- doesFileExist (profilePath args)
+      unless b usage
+      pure args
+
 main :: IO ()
 main = do
-  path:_ <- getArgs
-  profile <- parseProfile path
+  args <- parseArgs
+  profile <- parseProfile $ profilePath args
   void $ defaultMain app profile
 
 parseProfile :: FilePath -> IO Profile
diff --git a/viewprof.cabal b/viewprof.cabal
--- a/viewprof.cabal
+++ b/viewprof.cabal
@@ -1,5 +1,5 @@
 name: viewprof
-version: 0.0.0.12
+version: 0.0.0.13
 synopsis: Text-based interactive GHC .prof viewer
 description: Text-based interactive GHC .prof viewer
 homepage: https://github.com/maoe/viewprof
@@ -22,8 +22,9 @@
   main-is: viewprof.hs
   build-depends:
       base >= 4.9 && < 4.11
-    , brick >= 0.16 && < 0.30
+    , brick >= 0.16 && < 0.34
     , containers >= 0.5.7 && < 0.6
+    , directory >= 1.3 && < 1.4
     , ghc-prof >= 1.4 && < 1.5
     , lens >= 4.14 && < 4.16
     , scientific >= 0.3.4.4 && < 0.4