diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index d0285131..6fa57e47 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -1169,7 +1169,7 @@ typedef pair_type *pair;
 #define set_pair_as_expr(n,a,d) \
  (((pair)(n))->hdr.mark = gc_color_red, \
   ((pair)(n))->hdr.grayed = 0, \
-  ((pair)(n))->hdr.immutable = 0; \
+  ((pair)(n))->hdr.immutable = 0, \
   ((pair)(n))->tag = pair_tag, \
   ((pair)(n))->pair_car = a, \
   ((pair)(n))->pair_cdr = d, \