diff --git a/scheme/ikarus.boot.orig b/scheme/ikarus.boot.orig
index 63fff55..c606bfd 100644
Binary files a/scheme/ikarus.boot.orig and b/scheme/ikarus.boot.orig differ
diff --git a/scheme/ikarus.bytevectors.ss b/scheme/ikarus.bytevectors.ss
index 52763a9..11b11fd 100644
--- a/scheme/ikarus.bytevectors.ss
+++ b/scheme/ikarus.bytevectors.ss
@@ -1037,7 +1037,7 @@
                  ($fx< i ($bytevector-length bv)))
             (case endianness
               [(little) ($bytevector-ieee-single-native-ref bv i)]
-              ;[(big) ($bytevector-ieee-single-nonnative-ref bv i)]
+              [(big) ($bytevector-ieee-single-nonnative-ref bv i)]
               [else (error 'bytevector-ieee-single-ref 
                       "invalid endianness" endianness)])
             (error 'bytevector-ieee-single-ref "invalid index" i))
@@ -1068,7 +1068,7 @@
             (if (flonum? x)
                 (case endianness
                   [(little) ($bytevector-ieee-single-native-set! bv i x)]
-              ;    [(big) ($bytevector-ieee-single-nonnative-set! bv i x)]
+                  [(big) ($bytevector-ieee-single-nonnative-set! bv i x)]
                   [else (error 'bytevector-ieee-single-set! 
                           "invalid endianness" endianness)])
                 (error 'bytevector-ieee-single-set! "not a flonum" x))
diff --git a/scheme/pass-specify-rep-primops.ss b/scheme/pass-specify-rep-primops.ss
index 6cb7a33..e7000dc 100644
--- a/scheme/pass-specify-rep-primops.ss
+++ b/scheme/pass-specify-rep-primops.ss
@@ -1499,6 +1499,22 @@
        (prm 'int+ (T bv) (prm 'sra (T i) (K fixnum-shift)))
        (K (- disp-bytevector-data bytevector-tag))))])
 
+(define-primop $bytevector-ieee-single-nonnative-ref unsafe
+  [(V bv i)
+   (let ([bvoff (- disp-bytevector-data bytevector-tag)]
+         [floff (- disp-flonum-data vector-tag)])
+     (with-tmp ([x (prm 'alloc (K (align flonum-size)) (K vector-tag))])
+       (prm 'mset x (K (- vector-tag)) (K flonum-tag))
+       (with-tmp ([t (prm 'int+ (T bv) (prm 'sra (T i) (K fixnum-shift)))])
+         (with-tmp ([x0 (prm 'mref t (K bvoff))])
+           (prm 'bswap! x0 x0)
+           (prm 'mset x (K floff) x0)))
+       (prm 'fl:load-single x (K floff))
+       (prm 'fl:single->double)
+       (prm 'fl:store x (K floff))
+       x))])
+
+
 ;;; the following uses unsupported sse3 instructions
 ;(define-primop $bytevector-ieee-double-nonnative-set! unsafe
 ;  [(E bv i x)
@@ -1524,6 +1540,19 @@
          (prm 'bswap! x0 x0)
          (prm 'mset t (K bvoff) x0))))])
 
+(define-primop $bytevector-ieee-single-nonnative-set! unsafe
+  [(E bv i x)
+   (let ([bvoff (- disp-bytevector-data bytevector-tag)]
+         [floff (- disp-flonum-data vector-tag)])
+     (seq*
+       (prm 'fl:load (T x) (K floff))
+       (prm 'fl:double->single)
+       (with-tmp ([t (prm 'int+ (T bv)
+                        (prm 'sra (T i) (K fixnum-shift)))])
+         (prm 'fl:store-single t (K bvoff))
+         (with-tmp ([x0 (prm 'mref t (K bvoff))])
+           (prm 'bswap! x0 x0)
+           (prm 'mset t (K bvoff) x0)))))])
 /section)
 
 (section ;;; strings
diff --git a/scheme/tests/bytevectors.ss b/scheme/tests/bytevectors.ss
index 4408b53..8bffb9b 100644
--- a/scheme/tests/bytevectors.ss
+++ b/scheme/tests/bytevectors.ss
@@ -317,27 +317,24 @@
        (bytevector-ieee-single-set! v 0 17.0 'little)
        (bytevector-ieee-single-ref v 0 'little))]
 
-;    [(lambda (x) (= x 17.0))
-;     (let ([v (make-bytevector 8)])
-;       (bytevector-ieee-single-set! v 0 17.0 'big)
-;       (bytevector-ieee-single-ref v 0 'big))]
-;    
-;    [(lambda (x) (= x 17.0))
-;     (let ([v1 (make-bytevector 8)])
-;       (bytevector-ieee-single-set! v1 0 17.0 'little)
-;       (let ([v2 (u8-list->bytevector
-;                   (reverse (bytevector->u8-list v1)))])
-;         (bytevector-ieee-single-ref v2 0 'big)))]
-;
-;    [(lambda (x) (= x 17.0))
-;     (let ([v1 (make-bytevector 8)])
-;       (bytevector-ieee-single-set! v1 0 17.0 'big)
-;       (let ([v2 (u8-list->bytevector
-;                   (reverse (bytevector->u8-list v1)))])
-;         (bytevector-ieee-single-ref v2 0 'little)))]
-
-
+    [(lambda (x) (= x 17.0))
+     (let ([v (make-bytevector 4)])
+       (bytevector-ieee-single-set! v 0 17.0 'big)
+       (bytevector-ieee-single-ref v 0 'big))]
+    
+    [(lambda (x) (= x 17.0))
+     (let ([v1 (make-bytevector 4)])
+       (bytevector-ieee-single-set! v1 0 17.0 'little)
+       (let ([v2 (u8-list->bytevector
+                   (reverse (bytevector->u8-list v1)))])
+         (bytevector-ieee-single-ref v2 0 'big)))]
 
+    [(lambda (x) (= x 17.0))
+     (let ([v1 (make-bytevector 4)])
+       (bytevector-ieee-single-set! v1 0 17.0 'big)
+       (let ([v2 (u8-list->bytevector
+                   (reverse (bytevector->u8-list v1)))])
+         (bytevector-ieee-single-ref v2 0 'little)))]
 
     ))
 
diff --git a/scheme/todo-r6rs.ss b/scheme/todo-r6rs.ss
index 268dbf2..7c5fad2 100755
--- a/scheme/todo-r6rs.ss
+++ b/scheme/todo-r6rs.ss
@@ -379,10 +379,10 @@
     [bytevector-ieee-double-native-set!         C bv]
     [bytevector-ieee-double-ref                 C bv]
     [bytevector-ieee-double-set!                C bv]
-    [bytevector-ieee-single-native-ref          S bv]
-    [bytevector-ieee-single-native-set!         S bv]
-    [bytevector-ieee-single-ref                 S bv]
-    [bytevector-ieee-single-set!                S bv]
+    [bytevector-ieee-single-native-ref          C bv]
+    [bytevector-ieee-single-native-set!         C bv]
+    [bytevector-ieee-single-ref                 C bv]
+    [bytevector-ieee-single-set!                C bv]
     [bytevector-length                          C bv]
     [bytevector-s16-native-ref                  C bv]
     [bytevector-s16-native-set!                 C bv]