diff --git a/collects/syntax-color/lexer-contract.rkt b/collects/syntax-color/lexer-contract.rkt
new file mode 100644
index 0000000000..3344737331
--- /dev/null
+++ b/collects/syntax-color/lexer-contract.rkt
@@ -0,0 +1,34 @@
+#lang racket/base
+(require racket/contract/base
+         unstable/options)
+(provide lexer/c)
+
+(define lexer/c
+  (option/c
+   (or/c (->i ([in input-port?])
+              (values [txt any/c]
+                      [type symbol?]
+                      [paren (or/c symbol? #f)]
+                      [start (or/c exact-positive-integer? #f)]
+                      [end (start) 
+                           (if start
+                               (and/c exact-positive-integer?
+                                      (>=/c start))
+                               #f)]))
+         (->i ([in input-port?]
+               [offset exact-nonnegative-integer?]
+               [mode any/c])
+              (values [txt any/c]
+                      [type symbol?]
+                      [paren (or/c symbol? #f)]
+                      [start (or/c exact-positive-integer? #f)]
+                      [end (start) 
+                           (if start
+                               (and/c exact-positive-integer?
+                                      (>=/c start))
+                               #f)]
+                      [backup exact-nonnegative-integer?]
+                      [new-mode any/c])))
+   #:tester (λ (x) (and (procedure? x) 
+                        (or (procedure-arity-includes? x 1)
+                            (procedure-arity-includes? x 3))))))