diff --git a/collects/racket/private/vector-wraps.rkt b/collects/racket/private/vector-wraps.rkt
index 4b0eabf0ae..395bf2f57c 100644
--- a/collects/racket/private/vector-wraps.rkt
+++ b/collects/racket/private/vector-wraps.rkt
@@ -67,7 +67,7 @@
                              (let ([new-vec (if (eq? i (unsafe-fXvector-length vec))
                                                 (grow-fXvector vec)
                                                 vec)])
-                               (unsafe-fXvector-set! new-vec i (let () last-body ...))
+                               (fXvector-set! new-vec i (let () last-body ...))
                                (values new-vec (unsafe-fx+ i 1))))])
                 (shrink-fXvector vec i))))]
          [(for*/fXvector #:length length-expr #:fill fill-expr (for-clause ...) body ...)
diff --git a/collects/tests/racket/fixnum.rktl b/collects/tests/racket/fixnum.rktl
index c34d9d952f..d72e11b305 100644
--- a/collects/tests/racket/fixnum.rktl
+++ b/collects/tests/racket/fixnum.rktl
@@ -215,4 +215,12 @@
 (test-sequence [(2 4 6)] (in-fxvector (fxvector 1 2 3 4 5 6 7 8) 1 6 2))
 (test-sequence [(8 6 4)] (in-fxvector (fxvector 1 2 3 4 5 6 7 8) 7 2 -2))
 
+;; Check safety:
+(err/rt-test (for/fxvector ([i 5]) 8.0))
+(err/rt-test (for/fxvector #:length 5 ([i 5]) 8.0))
+(err/rt-test (for/fxvector #:length 5 #:fill 0 ([i 5]) 8.0))
+(err/rt-test (for/fxvector #:length 5 #:fill 0.0 ([i 5]) 8))
+(err/rt-test (for/fxvector #:length 10 #:fill 0.0 ([i 5]) 8))
+
+
 (report-errs)
diff --git a/collects/tests/racket/flonum.rktl b/collects/tests/racket/flonum.rktl
index ae6b1a9cfe..2d2740fd0a 100644
--- a/collects/tests/racket/flonum.rktl
+++ b/collects/tests/racket/flonum.rktl
@@ -157,6 +157,13 @@
 (test-sequence [(2.0 4.0 6.0)] (in-flvector (flvector 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0) 1 6 2))
 (test-sequence [(8.0 6.0 4.0)] (in-flvector (flvector 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0) 7 2 -2))
 
+;; Check safety:
+(err/rt-test (for/flvector ([i 5]) 8))
+(err/rt-test (for/flvector #:length 5 ([i 5]) 8))
+(err/rt-test (for/flvector #:length 5 #:fill 0.0 ([i 5]) 8))
+(err/rt-test (for/flvector #:length 5 #:fill 0 ([i 5]) 8.0))
+(err/rt-test (for/flvector #:length 10 #:fill 0 ([i 5]) 8.0))
+
 ;; ----------------------------------------
 ;; Check corners of `flexpt':
 ;;  Tests by Neil T.: