diff --git a/src/gc.c b/src/gc.c
index 3ee5da1f8..888e36620 100644
--- a/src/gc.c
+++ b/src/gc.c
@@ -883,7 +883,7 @@ mrb_gc_arena_restore(mrb_state *mrb, int idx)
 
 /*
  * Field write barrier
- *   Paint obj(Black) -> value(White) to obj(Black) -> value(Black).
+ *   Paint obj(Black) -> value(White) to obj(Black) -> value(Gray).
  */
 
 void