diff --git a/aeson-flowtyped.cabal b/aeson-flowtyped.cabal
--- a/aeson-flowtyped.cabal
+++ b/aeson-flowtyped.cabal
@@ -3,7 +3,7 @@
 -- see: https://github.com/sol/hpack
 
 name:           aeson-flowtyped
-version:        0.7.4
+version:        0.7.5
 synopsis:       Create Flow type definitions from Haskell data types.
 description:    Create Flow type definitions from Haskell data types.
 category:       Web
diff --git a/src/Data/Aeson/Flow.hs b/src/Data/Aeson/Flow.hs
--- a/src/Data/Aeson/Flow.hs
+++ b/src/Data/Aeson/Flow.hs
@@ -667,6 +667,11 @@
                      ]))
   flowTypeName _ = Just "Tree"
 
+instance FlowTyped () where
+  isPrim _ = False
+  flowType _ = Fix (Tuple V.empty)
+  flowTypeName _ = Nothing
+
 -- monomorphic numeric instances
 $(concat <$> mapM
   (\ty ->