diff --git a/include/cyclone/runtime.h b/include/cyclone/runtime.h
index 3607d637..8474f898 100644
--- a/include/cyclone/runtime.h
+++ b/include/cyclone/runtime.h
@@ -108,6 +108,9 @@ object cell_get(object cell);
 #define global_set(glo,value) Cyc_global_set(data, (object *)&glo, value)
 object Cyc_global_set(void *thd, object * glo, object value);
 
+#define global_set2(thd,k,glo,value) Cyc_global_set2(thd, k, (object *)&glo, value)
+object Cyc_global_set2(void *thd, object cont, object * glo, object value);
+
 /* Variable argument count support 
 
    This macro is intended to be executed at the top of a function that
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index e377e47a..65de20d4 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -524,6 +524,14 @@ void add_mutation(void *data, object var, int index, object value);
 void clear_mutations(void *data);
 /**@}*/
 
+/**
+ * \defgroup gc_minor_sh_obj Shared object write barrier
+ * @brief Minor GC write barrier to ensure there are no references to stack objects from the heap.
+ */
+/**@{*/
+object share_object(gc_thread_data *data, object var, object value, int *run_gc);
+/**@}*/
+
 /**@}*/
 
 // END GC section
diff --git a/runtime.c b/runtime.c
index eaea10a1..0e3a76c1 100644
--- a/runtime.c
+++ b/runtime.c
@@ -30,6 +30,20 @@ object Cyc_global_set(void *thd, object * glo, object value)
   return value;
 }
 
+object Cyc_global_set2(void *thd, object cont, object * glo, object value)
+{
+  int do_gc = 0;
+  value = share_object(thd, NULL, value, &do_gc);
+  gc_mut_update((gc_thread_data *) thd, *glo, value);
+  *(glo) = value;
+//  ((gc_thread_data *) thd)->globals_changed = 1; // No longer needed??
+  if (do_gc) {
+    object buf[1]; buf[0] = value;
+    GC(thd, cont, buf, 1);
+  }
+  return value;
+}
+
 /* Error checking section - type mismatch, num args, etc */
 /* Type names to use for error messages */
 const char *tag_names[] = {