diff --git a/src/Data/Bool.hs b/src/Data/Bool.hs
index be6d432..755a76f 100644
--- a/src/Data/Bool.hs
+++ b/src/Data/Bool.hs
@@ -13,6 +13,7 @@
 -- | Defines the boolean type and logical operators
 module Data.Bool where
 
+import Data.Kind      (Type)
 import Data.TypeClass (Eq, Enum, Show)
 import Data.Singletons.TH
 import Data.Singletons.Prelude.Enum
@@ -21,7 +22,7 @@ import Data.Singletons.Prelude.Enum
 singletons [d|
 
   -- | Boolean Type
-  data 𝔹 ∷ ★ where
+  data 𝔹 ∷ Type where
     T ∷ 𝔹 -- ^ True
     F ∷ 𝔹 -- ^ False
     deriving (Eq, Show)