1 files changed, 1 insertions, 0 deletions
diff --git a/vm_core.h b/vm_core.h
index 8d5b74c0fb..3fd26232db 100644
--- a/vm_core.h
+++ b/vm_core.h
@@ -442,6 +442,7 @@ struct rb_thread_struct
     struct rb_unblock_callback unblock;
     VALUE locking_mutex;
     VALUE keeping_mutexes;
+    int transition_for_lock;
 
     struct rb_vm_tag *tag;
     struct rb_vm_trap_tag *trap_tag;