diff --git a/Text/Pandoc/Definition.hs b/Text/Pandoc/Definition.hs
--- a/Text/Pandoc/Definition.hs
+++ b/Text/Pandoc/Definition.hs
@@ -66,6 +66,7 @@
 import Data.String
 import Data.Char (toLower)
 import Data.Monoid
+import Control.DeepSeq.Generics
 
 data Pandoc = Pandoc Meta [Block]
               deriving (Eq, Ord, Read, Show, Typeable, Data, Generic)
@@ -338,3 +339,18 @@
   where parseJSON = parseJSON'
 instance ToJSON Pandoc
   where toJSON = toJSON'
+
+-- Instances for deepseq
+instance NFData MetaValue where rnf = genericRnf
+instance NFData Meta where rnf = genericRnf
+instance NFData Citation where rnf = genericRnf
+instance NFData Alignment where rnf = genericRnf
+instance NFData Inline where rnf = genericRnf
+instance NFData MathType where rnf = genericRnf
+instance NFData Format where rnf = genericRnf
+instance NFData CitationMode where rnf = genericRnf
+instance NFData QuoteType where rnf = genericRnf
+instance NFData ListNumberDelim where rnf = genericRnf
+instance NFData ListNumberStyle where rnf = genericRnf
+instance NFData Block where rnf = genericRnf
+instance NFData Pandoc where rnf = genericRnf
diff --git a/pandoc-types.cabal b/pandoc-types.cabal
--- a/pandoc-types.cabal
+++ b/pandoc-types.cabal
@@ -1,5 +1,5 @@
 Name:                pandoc-types
-Version:             1.12.3.3
+Version:             1.12.4
 Synopsis:            Types for representing a structured document
 Description:         @Text.Pandoc.Definition@ defines the 'Pandoc' data
                      structure, which is used by pandoc to represent
@@ -46,4 +46,5 @@
                      syb >= 0.1 && < 0.5,
                      ghc-prim >= 0.2,
                      bytestring >= 0.9 && < 0.11,
-                     aeson >= 0.6.2 && < 0.8
+                     aeson >= 0.6.2 && < 0.8,
+                     deepseq-generics >= 0.1 && < 0.2