diff --git a/racket/collects/racket/sequence.rkt b/racket/collects/racket/sequence.rkt
index cd68cd305c..128d71cd17 100644
--- a/racket/collects/racket/sequence.rkt
+++ b/racket/collects/racket/sequence.rkt
@@ -41,8 +41,11 @@
 
 (define (sequence-length s)
   (unless (sequence? s) (raise-argument-error 'sequence-length "sequence?" s))
-  (for/fold ([c 0]) ([i (in-values*-sequence s)])
-    (add1 c)))
+  (cond [(vector? s) (vector-length s)]
+        [(hash? s) (hash-count s)]
+        [else
+         (for/fold ([c 0]) ([i (in-values*-sequence s)])
+           (add1 c))]))
 
 (define (sequence-ref s i)
   (unless (sequence? s) (raise-argument-error 'sequence-ref "sequence?" s))