diff --git a/gc.c b/gc.c
index b3199bab..fa3ca57b 100644
--- a/gc.c
+++ b/gc.c
@@ -634,7 +634,9 @@ void gc_handshake(gc_status_type s)
 
 void gc_post_handshake(gc_status_type s)
 {
+  int status = ATOMIC_GET(&gc_status_col);
   TODO: use atomic to change value of gc_status_col
+  while (!ATOMIC_SET_IF_EQ(&gc_status_col, status, s)){}
 }
 
 void gc_wait_handshake()
diff --git a/include/cyclone/types.h b/include/cyclone/types.h
index 330fb5d0..a4b35417 100644
--- a/include/cyclone/types.h
+++ b/include/cyclone/types.h
@@ -405,6 +405,6 @@ typedef union {
 #define ATOMIC_INC(ptr) __sync_fetch_and_add((ptr),1)
 #define ATOMIC_DEC(ptr) __sync_fetch_and_sub((ptr),1)
 #define ATOMIC_GET(ptr) __sync_fetch_and_add((ptr),0)
-#define ATOMIC_SET_IF_EQ(ptr, oldv, newv) __sync_val_compare_and_swap(ptr, oldv, newv)
+#define ATOMIC_SET_IF_EQ(ptr, oldv, newv) __sync_bool_compare_and_swap(ptr, oldv, newv)
 
 #endif /* CYCLONE_TYPES_H */