diff --git a/Setup.hs b/Setup.hs
index cf84de0355188f3e5b124b8a3a4a4a7761b100d6..c35fcf969c62dd27f796e4ba5b6634655f3d16e9 100644
--- a/Setup.hs
+++ b/Setup.hs
@@ -38,6 +38,7 @@ extractPrefixArgs prefix args
 
 removePrefix :: String -> String -> Maybe String
 removePrefix "" ys = Just ys
+removePrefix _  "" = Nothing
 removePrefix (x:xs) (y:ys)
  | x == y = removePrefix xs ys
  | otherwise = Nothing