diff --git a/gc.c b/gc.c
index 977a2966f7..62fbc6ff72 100644
--- a/gc.c
+++ b/gc.c
@@ -10796,7 +10796,7 @@ gc_update_references(rb_objspace_t *objspace)
 #if GC_CAN_COMPILE_COMPACTION
 /*
  *  call-seq:
- *     GC.latest_compact_info -> {:considered=>{:T_CLASS=>11}, :moved=>{:T_CLASS=>11}}
+ *     GC.latest_compact_info -> hash
  *
  * Returns information about object moved in the most recent GC compaction.
  *
diff --git a/gc.rb b/gc.rb
index 2fbef475e0..3912d35f4c 100644
--- a/gc.rb
+++ b/gc.rb
@@ -219,7 +219,7 @@ module GC
   end
 
   #  call-seq:
-  #     GC.latest_gc_info -> {:gc_by=>:newobj}
+  #     GC.latest_gc_info -> hash
   #     GC.latest_gc_info(hash) -> hash
   #     GC.latest_gc_info(:major_by) -> :malloc
   #