diff --git a/probability.cabal b/probability.cabal
--- a/probability.cabal
+++ b/probability.cabal
@@ -1,6 +1,6 @@
 Cabal-Version:      1.24
 Name:               probability
-Version:            0.2.9
+Version:            0.2.9.1
 License:            BSD3
 License-File:       COPYRIGHT
 Author:             Martin Erwig <erwig@eecs.oregonstate.edu>, Steve Kollmansberger
@@ -30,26 +30,17 @@
 Source-Repository this
   type:     darcs
   location: http://code.haskell.org/~thielema/probability/
-  tag:      0.2.9
+  tag:      0.2.9.1
 
 
-Flag splitBase
-  description: Choose the new smaller, split-up base package.
-
 Library
   Build-Depends:
     non-empty >=0.3 && <0.4,
     utility-ht >=0.0.12 && <0.1,
-    transformers >=0.4 && <0.7
-  If flag(splitBase)
-    Build-Depends:
-      containers >=0.1 && <0.9,
-      random >=1.0 && <1.4,
-      base >=2 && <5
-  Else
-    Build-Depends:
-      special-functors >=1.0 && <1.1,
-      base >=1.0 && <2
+    transformers >=0.4 && <0.7,
+    containers >=0.1 && <0.9,
+    random >=1.0 && <1.4,
+    base >=4.8 && <5
 
   Default-Language:   Haskell98
   GHC-Options:        -Wall
diff --git a/src/Numeric/Probability/Distribution.hs b/src/Numeric/Probability/Distribution.hs
--- a/src/Numeric/Probability/Distribution.hs
+++ b/src/Numeric/Probability/Distribution.hs
@@ -63,7 +63,6 @@
 certainly x = Cons [(x,1)]
 
 instance Num prob => Monad (T prob) where
-  return   = certainly
   d >>= f  = Cons [(y,q*p) | (x,p) <- decons d, (y,q) <- decons (f x)]
 
 instance Num prob => Applicative (T prob) where
diff --git a/src/Numeric/Probability/Random.hs b/src/Numeric/Probability/Random.hs
--- a/src/Numeric/Probability/Random.hs
+++ b/src/Numeric/Probability/Random.hs
@@ -20,7 +20,6 @@
 newtype T a = Cons {decons :: State Random.StdGen a}
 
 instance Monad T where
-   return x = Cons (return x)
    Cons x >>= y =
       Cons (decons . y =<< x)