diff --git a/bench/Bench.hs b/bench/Bench.hs
--- a/bench/Bench.hs
+++ b/bench/Bench.hs
@@ -3,7 +3,6 @@
 import           Criterion.Main
 import qualified Math.Combinat.Numbers                 as Ext
 import qualified Math.NumberTheory.ArithmeticFunctions as Ext
--- import qualified Math.NumberTheory.Moduli.Jacobi       as Ext
 import           Numeric.Combinatorics
 import           Numeric.Integer
 import           Numeric.NumberTheory
@@ -46,9 +45,5 @@
                 , bgroup "catalan"
                       [ bench "catalan" $ nf catalan 300
                       , bench "Ext.catalan" $ nf Ext.catalan (300 :: Int)
-                      ]
-                , bgroup "fibonacci"
-                      [ bench "fibonacci" $ nf fibonacci 200
-                      , bench "hsFibonacci" $ nf (hsFibonacci :: Int -> Integer) 200
                       ]
                 ]
diff --git a/fast-arithmetic.cabal b/fast-arithmetic.cabal
--- a/fast-arithmetic.cabal
+++ b/fast-arithmetic.cabal
@@ -1,6 +1,6 @@
 cabal-version: 1.18
 name: fast-arithmetic
-version: 0.3.3.5
+version: 0.3.3.6
 license: BSD3
 license-file: LICENSE
 copyright: Copyright: (c) 2018 Vanessa McHale
diff --git a/src/Numeric/Integer.hs b/src/Numeric/Integer.hs
--- a/src/Numeric/Integer.hs
+++ b/src/Numeric/Integer.hs
@@ -6,21 +6,12 @@
 -}
 
 module Numeric.Integer ( isPrime
-                       , fibonacci
                        ) where
 
-import           Data.GMP
 import           Foreign.C
-import           Foreign.Ptr
 import           Numeric.Common
-import           System.IO.Unsafe (unsafePerformIO)
 
 foreign import ccall is_prime_ats :: CInt -> CBool
-foreign import ccall unsafe fib_ats :: CInt -> Ptr GMPInt
-
--- | Indexed starting at @0@.
-fibonacci :: Int -> Integer
-fibonacci = unsafePerformIO . conjugateGMP fib_ats
 
 -- | \( O(\sqrt(n)) \)
 isPrime :: Int -> Bool
diff --git a/test/Spec.hs b/test/Spec.hs
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -60,6 +60,6 @@
 
     sequence_ $ zipWith4 check
         ["choose 101", "doubleFactorial", "catalan", "fibonacci", "factorial", "jacobi"]
-        [choose 101, doubleFactorial, catalan, fibonacci, factorial]
-        [Ext.binomial 101, Ext.doubleFactorial, Ext.catalan, hsFibonacci . fromIntegral, Ext.factorial]
+        [choose 101, doubleFactorial, catalan, factorial]
+        [Ext.binomial 101, Ext.doubleFactorial, Ext.catalan, Ext.factorial]
         [16, 79, 300, 121, 231]