diff --git a/collects/scribblings/reference/sequences.scrbl b/collects/scribblings/reference/sequences.scrbl
index 5de85ff3ac..ed0c7ff5e2 100644
--- a/collects/scribblings/reference/sequences.scrbl
+++ b/collects/scribblings/reference/sequences.scrbl
@@ -79,8 +79,17 @@ element. @speed[in-naturals "integer"]}
 Returns a sequence equivalent to @scheme[lst].
 @speed[in-list "list"]}
 
-@defproc[(in-vector [vec vector?]) sequence?]{
-Returns a sequence equivalent to @scheme[vec].
+@defproc[(in-vector [vec vector?] [start number?] [stop number?] [step number?]) sequence?]{
+Returns a sequence equivalent to @scheme[vec].  The optional
+arguments @scheme[start], @scheme[stop], and @scheme[step]
+are as for @scheme[in-range]. The single-argument case
+@scheme[(in-vector vec)] is equivalent to @scheme[(in-vector 0
+(vector-length vec) 1)].  The first number in the sequence is
+@scheme[start], and each successive element is generated by
+adding @scheme[step] to the previous element. The sequence
+stops before an element that would be greater or equal to
+@scheme[end] if @scheme[step] is non-negative, or less or
+equal to @scheme[end] if @scheme[step] is negative.
 @speed[in-vector "vector"]}
 
 @defproc[(in-string [str string?]) sequence?]{