diff --git a/src/ikarus.boot b/src/ikarus.boot
index 2fed51f..aa95941 100644
Binary files a/src/ikarus.boot and b/src/ikarus.boot differ
diff --git a/src/makefile.ss b/src/makefile.ss
index 87f932b..ee2a927 100755
--- a/src/makefile.ss
+++ b/src/makefile.ss
@@ -117,6 +117,7 @@
     [interaction (ikarus interaction)         #t]
     [r           (r6rs)                       #t]
     [syncase     (r6rs syntax-case)           #t]
+    [mutable-pairs (r6rs mutable-pairs)       #t]
     [cm          (chez modules)               #t]
     [$all        (ikarus system $all)         #f]
     [$pairs      (ikarus system $pairs)       #f]
@@ -237,8 +238,8 @@
     [pair?                   i r]
     [car                     i r]
     [cdr                     i r]
-    [set-car!                i]
-    [set-cdr!                i]
+    [set-car!                i mutable-pairs]
+    [set-cdr!                i mutable-pairs]
     [caar                    i r]
     [cdar                    i r]
     [cadr                    i r]