diff --git a/module/rnrs/arithmetic/fixnums.scm b/module/rnrs/arithmetic/fixnums.scm
index 7a5a6215e..4ec1cae0c 100644
--- a/module/rnrs/arithmetic/fixnums.scm
+++ b/module/rnrs/arithmetic/fixnums.scm
@@ -242,28 +242,50 @@
 
   (define (fxcopy-bit fx1 fx2 fx3) 
     (assert-fixnum fx1 fx2 fx3) 
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-copy-bit fx1 fx2 fx3))
 
   (define (fxbit-field fx1 fx2 fx3)
     (assert-fixnum fx1 fx2 fx3)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-bit-field fx1 fx2 fx3))
 
   (define (fxcopy-bit-field fx1 fx2 fx3 fx4)
     (assert-fixnum fx1 fx2 fx3 fx4)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-copy-bit-field fx1 fx2 fx3 fx4))
 
-  (define (fxarithmetic-shift fx1 fx2) (assert-fixnum fx1 fx2) (ash fx1 fx2))
-  (define fxarithmetic-shift-left fxarithmetic-shift)
+  (define (fxarithmetic-shift fx1 fx2)
+    (assert-fixnum fx1 fx2)
+    (unless (< (abs fx2) (fixnum-width))
+      (raise (make-assertion-violation)))
+    (ash fx1 fx2))
+
+  (define (fxarithmetic-shift-left fx1 fx2)
+    (assert-fixnum fx1 fx2)
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
+    (ash fx1 fx2))
 
   (define (fxarithmetic-shift-right fx1 fx2)
-    (assert-fixnum fx1 fx2) (ash fx1 (- fx2)))
+    (assert-fixnum fx1 fx2)
+    (unless (and (<= 0 fx2) (< fx2 (fixnum-width)))
+      (raise (make-assertion-violation)))
+    (ash fx1 (- fx2)))
 
   (define (fxrotate-bit-field fx1 fx2 fx3 fx4)
     (assert-fixnum fx1 fx2 fx3 fx4)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)) (< fx4 (- fx3 fx2)))
+      (raise (make-assertion-violation)))
     (bitwise-rotate-bit-field fx1 fx2 fx3 fx4))
   
   (define (fxreverse-bit-field fx1 fx2 fx3)
     (assert-fixnum fx1 fx2 fx3)
+    (unless (and (<= 0 fx2 fx3) (< fx3 (fixnum-width)))
+      (raise (make-assertion-violation)))
     (bitwise-reverse-bit-field fx1 fx2 fx3))
 
 )
diff --git a/test-suite/tests/r6rs-arithmetic-fixnums.test b/test-suite/tests/r6rs-arithmetic-fixnums.test
index 2d9b177f7..9f244722f 100644
--- a/test-suite/tests/r6rs-arithmetic-fixnums.test
+++ b/test-suite/tests/r6rs-arithmetic-fixnums.test
@@ -202,7 +202,7 @@
 	 (fx=? (fxarithmetic-shift -1 -1) -1))))
 
 (with-test-prefix "fxarithmetic-shift-left"
-  (pass-if "simple" (fx=? (fxarithmetic-shift-left -6 -1) -3)))
+  (pass-if "simple" (fx=? (fxarithmetic-shift-left -6 1) -12)))
 
 (with-test-prefix "fxarithmetic-shift-right"
   (pass-if "simple" (fx=? (fxarithmetic-shift-right -6 1) -3)))