diff --git a/collects/typed-scheme/private/base-env.rkt b/collects/typed-scheme/private/base-env.rkt
index 8054c0c0..d3d251bf 100644
--- a/collects/typed-scheme/private/base-env.rkt
+++ b/collects/typed-scheme/private/base-env.rkt
@@ -280,7 +280,17 @@
 [fprintf (->* (list -Output-Port -String) Univ -Void)]
 [format (->* (list -String) Univ -String)]
 
-[sleep (N . -> . -Void)]
+[thread (-> (-> Univ) -Thread)]
+[thread? (make-pred-ty -Thread)]
+[current-thread (-> -Thread)]
+[thread/suspend-to-kill (-> (-> Univ) -Thread)]
+[thread-suspend (-Thread . -> . -Void)]
+[kill-thread (-Thread . -> . -Void)]
+[break-thread (-Thread . -> . -Void)]
+[sleep ([N] . ->opt . -Void)]
+[thread-running? (-Thread . -> . B)]
+[thread-dead? (-Thread . -> . B)]
+[thread-wait (-Thread . -> . -Void)]
 
 [reverse (-poly (a) (-> (-lst a) (-lst a)))]
 [append (-poly (a) (->* (list) (-lst a) (-lst a)))]
diff --git a/collects/typed-scheme/private/base-types-new.rkt b/collects/typed-scheme/private/base-types-new.rkt
index 8dbf20df..d5a8cc81 100644
--- a/collects/typed-scheme/private/base-types-new.rkt
+++ b/collects/typed-scheme/private/base-types-new.rkt
@@ -35,6 +35,7 @@
 [Identifier Ident]
 [Procedure top-func]
 [Keyword -Keyword]
+[Thread -Thread]
 [Listof -Listof]
 [Vectorof (-poly (a) (make-Vector a))]
 [FlVector -FlVector]
diff --git a/collects/typed-scheme/types/abbrev.rkt b/collects/typed-scheme/types/abbrev.rkt
index a15c22c2..9bdfbb75 100644
--- a/collects/typed-scheme/types/abbrev.rkt
+++ b/collects/typed-scheme/types/abbrev.rkt
@@ -93,6 +93,7 @@
 (define -String (make-Base 'String #'string?))
 (define -Keyword (make-Base 'Keyword #'keyword?))
 (define -Char (make-Base 'Char #'char?))
+(define -Thread (make-Base 'Thread #'thread?))
 (define -Prompt-Tag (make-Base 'Prompt-Tag #'continuation-prompt-tag?))
 (define -Cont-Mark-Set (make-Base 'Continuation-Mark-Set #'continuation-mark-set?))
 (define -Path (make-Base 'Path #'path?))