diff --git a/PC/config.h b/PC/config.h
index 16f82e1..850af58 100644
--- a/PC/config.h
+++ b/PC/config.h
@@ -452,7 +452,7 @@
 /* #define WITH_READLINE 1 */
 
 /* Define if you want cycle garbage collection */
-/* #define WITH_CYCLE_GC 1 */
+#define WITH_CYCLE_GC 1
 
 /* Define if you have clock.  */
 /* #define HAVE_CLOCK */