diff --git a/thread.c b/thread.c
index ad35c103e7..4b769506ef 100644
--- a/thread.c
+++ b/thread.c
@@ -2673,7 +2673,6 @@ static void
 timer_thread_function(void *arg)
 {
     rb_vm_t *vm = GET_VM(); /* TODO: fix me for Multi-VM */
-    rb_thread_t *mth;
 
     /* for time slice */
     RUBY_VM_SET_TIMER_INTERRUPT(vm->running_thread);