diff --git a/src/typechecker/environment.lisp b/src/typechecker/environment.lisp
index 30df4206..3d11f617 100644
--- a/src/typechecker/environment.lisp
+++ b/src/typechecker/environment.lisp
@@ -859,6 +859,7 @@
                              (source-name-environment (environment-source-name-environment env)))
   (declare (type environment env)
            (type value-environment value-environment)
+           (type type-environment type-environment)
            (type constructor-environment constructor-environment)
            (type struct-environment struct-environment)
            (type class-environment class-environment)