diff --git a/mmtf.cabal b/mmtf.cabal
--- a/mmtf.cabal
+++ b/mmtf.cabal
@@ -1,5 +1,5 @@
 name:                mmtf
-version:             0.1.3.0
+version:             0.1.3.1
 synopsis:            Macromolecular Transmission Format implementation
 description:         Haskell implementation of MMTF biological structure format.
 homepage:            https://github.com/zmactep/mmtf#readme
@@ -56,6 +56,7 @@
                      , containers
                      , http-conduit
                      , array
+                     , deepseq
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N
   default-language:    Haskell2010