diff --git a/lib/Cryptol.cry b/lib/Cryptol.cry
index 2a4b2b1b..5879f753 100644
--- a/lib/Cryptol.cry
+++ b/lib/Cryptol.cry
@@ -57,7 +57,7 @@ primitive type (!=) : # -> # -> Prop
 primitive type (>=) : # -> # -> Prop
 
 /** Assert that a numeric type is a proper natural number (not 'inf'). */
-primitive type fin : * -> Prop
+primitive type fin : # -> Prop
 
 /** Value types that have a notion of 'zero'. */
 primitive type Zero : * -> Prop
diff --git a/src/Cryptol/TypeCheck/Type.hs b/src/Cryptol/TypeCheck/Type.hs
index 04c8ca08..f21b7515 100644
--- a/src/Cryptol/TypeCheck/Type.hs
+++ b/src/Cryptol/TypeCheck/Type.hs
@@ -292,7 +292,15 @@ newtypeConType nt =
 abstractTypeTC :: AbstractType -> TCon
 abstractTypeTC at =
   case builtInType (atName at) of
-    Just tcon -> tcon
+    Just tcon
+      | kindOf tcon == atKind at -> tcon
+      | otherwise ->
+        panic "abstractTypeTC"
+          [ "Mismatch between built-in and declared type."
+          , "Name: " ++ pretty (atName at)
+          , "Declared: " ++ pretty (atKind at)
+          , "Built-in: " ++ pretty (kindOf tcon)
+          ]
     _         -> TC $ TCAbstract $ UserTC (atName at) (atKind at)
 
 instance Eq TVar where
diff --git a/tests/issues/issue226.icry.stdout b/tests/issues/issue226.icry.stdout
index 5154a3e2..5c8e4812 100644
--- a/tests/issues/issue226.icry.stdout
+++ b/tests/issues/issue226.icry.stdout
@@ -44,7 +44,7 @@ Primitive Types
     Arith : * -> Prop
     Bit : *
     Cmp : * -> Prop
-    fin : * -> Prop
+    fin : # -> Prop
     Integer : *
     inf : #
     Literal : # -> * -> Prop