diff --git a/thread.c b/thread.c
index 95b045fc54..7b343a522d 100644
--- a/thread.c
+++ b/thread.c
@@ -2870,7 +2870,7 @@ rb_thread_variable_get(VALUE thread, VALUE id)
     GetThreadPtr(thread, th);
 
     if (rb_safe_level() >= 4 && th != GET_THREAD()) {
-	rb_raise(rb_eSecurityError, "Insecure: can't modify thread locals");
+	rb_raise(rb_eSecurityError, "Insecure: can't access thread locals");
     }
 
     locals = rb_iv_get(thread, "locals");