diff --git a/Main.hs b/Main.hs
--- a/Main.hs
+++ b/Main.hs
@@ -1,6 +1,6 @@
 module Main ( main ) where
 
-import Hledger
+import Hledger hiding (multiplyAmount)
 
 import Control.Exception ( bracket )
 import Control.Monad
@@ -13,9 +13,10 @@
 import Text.Printf
 import Data.List
 import Data.Ord
-import Statistics.Math.RootFinding
+import Numeric.RootFinding
 import Data.Decimal
 import qualified Data.Text as T
+import Data.Default.Class
 
 
 import Paths_hledger_irr ( version )
@@ -150,7 +151,7 @@
 
       -- 0% is always a solution, so require at least something here
       putStr $ printf "%s - %s: " (showDate ibegin) (showDate iend)
-      case ridders 0.00001 (0.000001,1000) (realToFrac . aquantity . interestSum iend totalCF) of
+      case ridders def (0.000001,1000) (realToFrac . aquantity . interestSum iend totalCF) of
         Root rate -> putStrLn (printf "%0.2f%%" ((rate-1)*100))
         _ -> putStrLn "Error: Failed to find solution."
 
diff --git a/hledger-irr.cabal b/hledger-irr.cabal
--- a/hledger-irr.cabal
+++ b/hledger-irr.cabal
@@ -1,5 +1,5 @@
 Name:                   hledger-irr
-Version:                0.1.1.15
+Version:                0.1.1.16
 Synopsis:               computes the internal rate of return of an investment
 License:                BSD3
 License-file:           LICENSE
@@ -64,11 +64,11 @@
  > 2011/04/01: €-50.00
  > 2011/05/01: €47.00
  > 2011/06/01: €90.00
- > 2011/01/01 - 2018/07/02: -100.00%
+ > 2011/01/01 - 2019/10/06: -100.00%
  > $ hledger-irr -f speculation.ledger -t "Rate Gain" -i Speculation -e 2011-03-01
  > 2011/01/01 - 2011/03/01: 26.12%
  > $ hledger-irr -f speculation.ledger -t "Rate Gain" -i Speculation -b 2011-03-01
- > 2011/03/01 - 2018/07/02: -100.00%
+ > 2011/03/01 - 2019/10/06: -100.00%
  > $ hledger-irr -f speculation.ledger -t "Rate Gain" -i Speculation --monthly
  > 2011/01/01 - 2011/02/01: 12.49%
  > 2011/02/01 - 2011/03/01: 41.55%
@@ -110,7 +110,8 @@
     Decimal,
     time,
     Cabal,
-    statistics >= 0.10,
+    data-default-class,
+    math-functions == 0.3.*,
     text
   Ghc-Options:          -Wall