diff --git a/compile.c b/compile.c
index 50136b483e..7de1da8694 100644
--- a/compile.c
+++ b/compile.c
@@ -3090,9 +3090,14 @@ compile_array_(rb_iseq_t *iseq, LINK_ANCHOR *const ret, NODE* node_root,
 			    ADD_INSN(ret, line, concatarray);
 			}
 			else {
+#if 0
 			    ADD_INSN1(ret, line, putspecialobject, INT2FIX(VM_SPECIAL_OBJECT_VMCORE));
 			    ADD_INSN1(ret, line, putobject, ary);
 			    ADD_SEND(ret, line, id_core_hash_merge_ary, INT2FIX(1));
+			    /* wrong number of arguments -----------------------^ */
+#else
+			    compile_bug(ERROR_ARGS "core#hash_merge_ary");
+#endif
 			}
 		    }
 		}
diff --git a/vm.c b/vm.c
index 67a6e8e164..b00a3e3505 100644
--- a/vm.c
+++ b/vm.c
@@ -2625,12 +2625,14 @@ core_hash_from_ary(VALUE ary)
     return core_hash_merge_ary(hash, ary);
 }
 
+#if 0
 static VALUE
 m_core_hash_merge_ary(VALUE self, VALUE hash, VALUE ary)
 {
     REWIND_CFP(core_hash_merge_ary(hash, ary));
     return hash;
 }
+#endif
 
 static VALUE
 core_hash_merge_ary(VALUE hash, VALUE ary)
@@ -2757,7 +2759,9 @@ Init_VM(void)
     rb_define_method_id(klass, id_core_define_singleton_method, m_core_define_singleton_method, 3);
     rb_define_method_id(klass, id_core_set_postexe, m_core_set_postexe, 0);
     rb_define_method_id(klass, id_core_hash_from_ary, m_core_hash_from_ary, 1);
+#if 0
     rb_define_method_id(klass, id_core_hash_merge_ary, m_core_hash_merge_ary, 2);
+#endif
     rb_define_method_id(klass, id_core_hash_merge_ptr, m_core_hash_merge_ptr, -1);
     rb_define_method_id(klass, id_core_hash_merge_kwd, m_core_hash_merge_kwd, -1);
     rb_define_method_id(klass, idProc, rb_block_proc, 0);