diff --git a/diversity.cabal b/diversity.cabal
--- a/diversity.cabal
+++ b/diversity.cabal
@@ -2,7 +2,7 @@
 -- documentation, see http://haskell.org/cabal/users-guide/
 
 name:                diversity
-version:             0.4.0.1
+version:             0.4.0.2
 synopsis:            Return the diversity at each position for all sequences in a fasta file
 description:         Find the diversity of a collection of entities, mainly for use with fasta sequences. Produces a binary which works on fasta files to find the diversity of any order and rarefaction curves for a sliding window across all positions in the sequences. To analyze just a collection of entities, just use the whole sequences and list flag.
 homepage:            https://github.com/GregorySchwartz/diversity
@@ -20,7 +20,7 @@
   hs-source-dirs:      src/src-lib
   exposed-modules:     Math.Diversity.Types, Math.Diversity.Diversity, Math.Diversity.GenerateDiversity, Math.Diversity.Print
   -- other-modules:
-  build-depends:       base >=4.6 && <4.8, containers >=0.5 && <0.6, split >=0.2 && <0.3, parsec >=3.1 && <4.0, fasta >=0.5.1.3 && <0.6, math-functions >=0.1 && <0.2
+  build-depends:       base >=4.6 && <4.8, containers >=0.5 && <0.6, split >=0.2 && <0.3, parsec >=3.1 && <4.0, fasta >=0.5.1.3 && <0.6, math-functions >=0.1 && <0.2, scientific >= 0.3 && < 0.4
 
 executable diversity
   ghc-options: -O2
diff --git a/src/src-exec/Main.hs b/src/src-exec/Main.hs
--- a/src/src-exec/Main.hs
+++ b/src/src-exec/Main.hs
@@ -84,7 +84,9 @@
           ( long "fast-bin"
          <> short 'f'
          <> help "Whether to use a much faster, but approximated, binomial\
-                 \ coefficient for the rarefaction analysis" )
+                 \ coefficient for the rarefaction analysis. This method\
+                 \ results in NaNs for larger numbers, so in that case you\
+                 \ you should use the slower, more accurate default method" )
       <*> switch
           ( long "remove-N"
          <> short 'n'