18008.patch

diff --git a/struct.c b/struct.c
index ceb025ff83..6fc489e3a2 100644
--- a/struct.c
+++ b/struct.c
@@ -1401,6 +1401,8 @@ InitVM_Struct(void)
     rb_undef_alloc_func(rb_cStruct);
     rb_define_singleton_method(rb_cStruct, "new", rb_struct_s_def, -1);
 
+    rb_define_singleton_method(rb_cStruct, "keyword_init?", rb_struct_s_keyword_init, 0);
+
     rb_define_method(rb_cStruct, "initialize", rb_struct_initialize_m, -1);
     rb_define_method(rb_cStruct, "initialize_copy", rb_struct_init_copy, 1);