diff --git a/scheme/ikarus.boot.orig b/scheme/ikarus.boot.orig
index a5847b5..d52ebee 100644
Binary files a/scheme/ikarus.boot.orig and b/scheme/ikarus.boot.orig differ
diff --git a/scheme/psyntax.expander.ss b/scheme/psyntax.expander.ss
index 883c871..8093f28 100644
--- a/scheme/psyntax.expander.ss
+++ b/scheme/psyntax.expander.ss
@@ -1031,33 +1031,50 @@
   
   (define guard-macro
     (lambda (x)
-      (syntax-match x (else)
-        [(_ (con clause* ... [else e e* ...]) b b* ...)
-         (bless
-           `((call/cc
-               (lambda (outerk)
-                 (lambda ()
-                   (with-exception-handler
-                     (lambda (,con)
-                       (outerk 
-                         (lambda () 
-                           (cond ,@clause* [else ,e ,@e*]))))
-                     (lambda () #f ,b ,@b*)))))))]
+      (define (gen-clauses con outerk clause*) 
+        (define (f x k) 
+          (syntax-match x (=>) 
+            [(e => p) 
+             (let ([t (gensym)])
+               `(let ([,t ,e]) 
+                  (if ,t (,p ,t) ,k)))]
+            [(e) 
+             (let ([t (gensym)])
+               `(let ([,t ,e])
+                  (if ,t ,t ,k)))]
+            [(e v v* ...) 
+             `(if ,e (begin ,v ,@v*) ,k)]
+            [_ (stx-error x "invalid guard clause")]))
+        (define (f* x*)
+          (syntax-match x* (else)
+            [() 
+             (let ([g (gensym)])
+               (values `(,g (lambda () (raise ,con))) g))]
+            [([else e e* ...])
+             (values `(begin ,e ,@e*) #f)]
+            [(cls . cls*) 
+             (let-values ([(e g) (f* cls*)])
+               (values (f cls e) g))]
+            [others (stx-error others "invalid guard clause")]))
+        (let-values ([(code raisek) (f* clause*)])
+          (if raisek
+              `((call/cc
+                  (lambda (,raisek)
+                    (,outerk 
+                      (lambda () ,code)))))
+              `(,outerk (lambda () ,code)))))
+      (syntax-match x ()
         [(_ (con clause* ...) b b* ...)
-         (bless
-           `((call/cc
-               (lambda (outerk)
-                 (lambda ()
-                   (with-exception-handler
-                     (lambda (,con) 
-                       ((call/cc
-                          (lambda (raisek)
-                            (outerk 
-                              (lambda () 
-                                (cond ,@clause* 
-                                  [else 
-                                   (raisek (lambda () (raise ,con)))])))))))
-                     (lambda () #f ,b ,@b* )))))))])))
+         (id? con)
+         (let ([outerk (gensym)])
+           (bless
+             `((call/cc
+                 (lambda (,outerk)
+                   (lambda ()
+                     (with-exception-handler
+                       (lambda (,con)
+                         ,(gen-clauses con outerk clause*))
+                       (lambda () #f ,b ,@b*))))))))])))
 
   (define time-macro
     (lambda (stx)
diff --git a/scheme/todo-r6rs.ss b/scheme/todo-r6rs.ss
index e2cd818..b7fcf2e 100755
--- a/scheme/todo-r6rs.ss
+++ b/scheme/todo-r6rs.ss
@@ -487,19 +487,19 @@
     [when                                       C ct]
     ;;;
     [define-enumeration                         D en]
-    [enum-set->list                             D en]
-    [enum-set-complement                        D en]
-    [enum-set-constructor                       D en]
-    [enum-set-difference                        D en]
-    [enum-set-indexer                           D en]
-    [enum-set-intersection                      D en]
-    [enum-set-member?                           D en]
-    [enum-set-projection                        D en]
-    [enum-set-subset?                           D en]
-    [enum-set-union                             D en]
-    [enum-set-universe                          D en]
-    [enum-set=?                                 D en]
-    [make-enumeration                           D en]
+    [enum-set->list                             C en]
+    [enum-set-complement                        C en]
+    [enum-set-constructor                       C en]
+    [enum-set-difference                        C en]
+    [enum-set-indexer                           C en]
+    [enum-set-intersection                      C en]
+    [enum-set-member?                           C en]
+    [enum-set-projection                        C en]
+    [enum-set-subset?                           C en]
+    [enum-set-union                             C en]
+    [enum-set-universe                          C en]
+    [enum-set=?                                 C en]
+    [make-enumeration                           C en]
     ;;;
     [environment                                C ev]
     [eval                                       C ev se]