Starting with ghc-7.4 base and haskell98 are incompatible:

 Ambiguous module name `Prelude':
  it was found in multiple packages: base haskell98-2.0.0.1

Gentoo-bug: https://bugs.gentoo.org/428226
Reported-by:  Chris Reffett
diff --git a/Bustle/Noninteractive.hs b/Bustle/Noninteractive.hs
index 2aa1e05..4a4d9b0 100644
--- a/Bustle/Noninteractive.hs
+++ b/Bustle/Noninteractive.hs
@@ -3,7 +3,8 @@ where
 
 import Prelude hiding (log)
 
-import System
+import System.Environment (getArgs)
+import System.Exit (exitFailure)
 import System.IO (hPutStrLn, stderr)
 
 import Bustle.Parser (readLog)
diff --git a/Bustle/Stats.hs b/Bustle/Stats.hs
index da374a5..939cafd 100644
--- a/Bustle/Stats.hs
+++ b/Bustle/Stats.hs
@@ -36,7 +36,7 @@ frequencies = reverse
     where alt Nothing  = Just 1
           alt (Just n) = Just (n + 1)
 
-mean :: Fractional a => [a] -> a
+mean :: (Eq a, Fractional a) => [a] -> a
 mean = acc 0 0
    where acc 0 _ [] = error "mean of empty list"
          acc n t [] = t / n
diff --git a/bustle-dot.hs b/bustle-dot.hs
index aa7c45e..77d6f18 100644
--- a/bustle-dot.hs
+++ b/bustle-dot.hs
@@ -3,7 +3,9 @@ import Prelude hiding (log)
 import Control.Monad
 import Data.List
 import Data.Maybe
-import System
+import System.IO
+import System.Environment
+import System.Exit
 
 import Bustle.Parser (readLog)
 import Bustle.Types
diff --git a/bustle.cabal b/bustle.cabal
index 7ad7412..0a49ca1 100644
--- a/bustle.cabal
+++ b/bustle.cabal
@@ -27,11 +27,11 @@ Executable bustle
   if flag(PostCabalizedGtk2HS)
     -- Since gtk2hs 0.11, pango is a separate package, and its module names
     -- have changed.
-    Build-Depends:  haskell98, mtl, base >= 4 && < 5, containers, parsec,
+    Build-Depends:  mtl, base >= 4 && < 5, containers, parsec,
                     filepath, process,
                     gtk > 0.11, glade, pango, glib, cairo
   else
-    Build-Depends:  haskell98, mtl, base >= 4 && < 5, containers, parsec,
+    Build-Depends:  mtl, base >= 4 && < 5, containers, parsec,
                     filepath, process,
                     gtk > 0.10 && < 0.11, glade, pango, glib, cairo
 
@@ -39,18 +39,18 @@ Executable bustle-count
   Main-is:        bustle-count.hs
   Other-modules:  Bustle.Parser, Bustle.Stats, Bustle.Types,
                   Bustle.Noninteractive
-  Build-Depends:  haskell98, base >= 4 && < 5, containers, parsec
+  Build-Depends:  base >= 4 && < 5, containers, parsec
   Ghc-options:    -Wall -fno-warn-unused-imports -fno-warn-unused-do-bind
 
 Executable bustle-time
   Main-is:        bustle-time.hs
   Other-modules:  Bustle.Parser, Bustle.Stats, Bustle.Types,
                   Bustle.Noninteractive
-  Build-Depends:  haskell98, base >= 4 && < 5, containers, parsec
+  Build-Depends:  base >= 4 && < 5, containers, parsec
   Ghc-options:    -Wall -fno-warn-unused-imports -fno-warn-unused-do-bind
 
 Executable bustle-dot
   Main-is:        bustle-dot.hs
   Other-modules:  Bustle.Parser, Bustle.Types
-  Build-Depends:  haskell98, base >= 4 && < 5, containers, parsec
+  Build-Depends:  base >= 4 && < 5, containers, parsec
   Ghc-options:    -Wall -fno-warn-unused-imports -fno-warn-unused-do-bind