diff --git a/lib/srfi/142/bitwise.scm b/lib/srfi/142/bitwise.scm
index 578bf095..7dff4b0b 100644
--- a/lib/srfi/142/bitwise.scm
+++ b/lib/srfi/142/bitwise.scm
@@ -76,30 +76,32 @@
 (define (bit-field-replace-same dst src start end)
   (bitwise-if (range start end) src dst))
 
-(define (bit-rotate i count)
-  (let ((len (integer-length i)))
-    (bit-ior (bit-and (arithmetic-shift i count) (mask len))
-             (arithmetic-shift i (- count len)))))
+(define (bit-field-rotate n count start end)
+  (let* ((width (- end start))
+         (count (modulo count width))
+         (mask (bitwise-not (arithmetic-shift -1 width)))
+         (n^ (bitwise-and mask (arithmetic-shift n (- start)))))
+    (bit-ior (arithmetic-shift
+              (bit-ior (bit-and mask (arithmetic-shift n^ count))
+                       (arithmetic-shift n^ (- count width)))
+              start)
+             (bit-and (bitwise-not (arithmetic-shift mask start)) n))))
 
-(define (bit-field-rotate i count start end)
-  (bitwise-if (range start end)
-              i
-              (arithmetic-shift (bit-rotate (bit-field i start end) count)
-                                start)))
-
-(define (bit-reverse i)
-  (let ((len (integer-length i)))
-    (let lp ((i i) (res 0))
-      (if (zero? i)
-          res
-          (lp (arithmetic-shift i -1)
-              (bit-ior (arithmetic-shift res 1)
-                       (bit-and i 1)))))))
+(define (bit-reverse n len)
+  (let lp ((n n) (i 1) (res 0))
+    (if (> i len)
+        res
+        (lp (arithmetic-shift n -1)
+            (+ i 1)
+            (bit-ior (arithmetic-shift res 1)
+                     (bit-and n 1))))))
 
 (define (bit-field-reverse i start end)
   (bitwise-if (range start end)
-              i
-              (arithmetic-shift (bit-reverse (bit-field i start end)) start)))
+              (arithmetic-shift (bit-reverse (bit-field i start end)
+                                             (- end start))
+                                start)
+              i))
 
 (define (vector->integer vec)
   (let ((len (vector-length vec)))
diff --git a/lib/srfi/142/test.sld b/lib/srfi/142/test.sld
index 5e1ef066..cca2bf04 100644
--- a/lib/srfi/142/test.sld
+++ b/lib/srfi/142/test.sld
@@ -151,4 +151,38 @@
       (test #b101010101
           (bitwise-unfold (lambda (i) (= i 10)) even? (lambda (i) (+ i 1)) 0))
 
+      (test #b110  (bit-field-rotate #b110 1 1 2))
+      (test #b1010 (bit-field-rotate #b110 1 2 4))
+      (test #b1011 (bit-field-rotate #b0111 -1 1 4))
+      (test #b0  (bit-field-rotate #b0 128 0 256))
+      (test #b1  (bit-field-rotate #b1 128 1 256))
+      (test #x100000000000000000000000000000000 
+	    (bit-field-rotate #x100000000000000000000000000000000 128 0 64))
+      (test #x100000000000000000000000000000008 
+	    (bit-field-rotate #x100000000000000000000000000000001 3 0 64))
+      (test #x100000000000000002000000000000000 
+	    (bit-field-rotate #x100000000000000000000000000000001 -3 0 64))
+      (test #b110 (bit-field-rotate #b110 0 0 10))
+      (test #b110 (bit-field-rotate #b110 0 0 256))
+      (test 1 (bit-field-rotate #x100000000000000000000000000000000 1 0 129))
+
+      (test 6 (bit-field-reverse 6 1 3))
+      (test 12 (bit-field-reverse 6 1 4))
+      (test #x80000000 (bit-field-reverse 1 0 32))
+      (test #x40000000 (bit-field-reverse 1 0 31))
+      (test #x20000000 (bit-field-reverse 1 0 30))
+      (test (bitwise-ior (arithmetic-shift -1 32) #xFBFFFFFF) 
+        (bit-field-reverse -2 0 27))
+      (test (bitwise-ior (arithmetic-shift -1 32) #xF7FFFFFF) 
+        (bit-field-reverse -2 0 28))
+      (test (bitwise-ior (arithmetic-shift -1 32) #xEFFFFFFF) 
+        (bit-field-reverse -2 0 29))
+      (test (bitwise-ior (arithmetic-shift -1 32) #xDFFFFFFF) 
+        (bit-field-reverse -2 0 30))
+      (test (bitwise-ior (arithmetic-shift -1 32) #xBFFFFFFF) 
+        (bit-field-reverse -2 0 31))
+      (test (bitwise-ior (arithmetic-shift -1 32) #x7FFFFFFF) 
+        (bit-field-reverse -2 0 32))
+      (test 5 (bit-field-reverse #x140000000000000000000000000000000 0 129))
+
       (test-end))))