diff --git a/src/Data/Abstract/Type.hs b/src/Data/Abstract/Type.hs
index 9585097c9..5b93258cd 100644
--- a/src/Data/Abstract/Type.hs
+++ b/src/Data/Abstract/Type.hs
@@ -7,6 +7,7 @@ import Prelude hiding (fail)
 -- | The type of type variable names.
 type TName = Int
 
+-- | A datatype representing primitive types and combinations thereof.
 data Type
   = Int
   | Bool