diff --git a/Data/These.hs b/Data/These.hs
--- a/Data/These.hs
+++ b/Data/These.hs
@@ -172,6 +172,7 @@
 
 -- | Select each constructor and partition them into separate lists.
 partitionThese :: [These a b] -> ( [(a, b)], ([a], [b]) )
+partitionThese []             = ([], ([], []))
 partitionThese (These x y:xs) = first ((x, y):)      $ partitionThese xs
 partitionThese (This  x  :xs) = second (first  (x:)) $ partitionThese xs
 partitionThese (That    y:xs) = second (second (y:)) $ partitionThese xs
diff --git a/these.cabal b/these.cabal
--- a/these.cabal
+++ b/these.cabal
@@ -1,5 +1,5 @@
 Name:                these
-Version:             0.4
+Version:             0.4.1
 Synopsis:            An either-or-both data type, with corresponding hybrid error/writer monad transformer.
 Homepage:            https://github.com/isomorphism/these
 License:             BSD3