diff --git a/vm_args.c b/vm_args.c
index 6fce593bf1..4ae0d6d7fc 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -735,15 +735,7 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
         rest_last = RARRAY_AREF(args->rest, len - 1);

         if (!kw_flag && len > 0) {
-            if (RB_TYPE_P(rest_last, T_HASH) &&
-                (((struct RHash *)rest_last)->basic.flags & RHASH_PASS_AS_KEYWORDS)) {
-                rest_last = rb_hash_dup(rest_last);
-                RARRAY_ASET(args->rest, len - 1, rest_last);
-                kw_flag |= VM_CALL_KW_SPLAT;
-            }
-            else {
-                rest_last = 0;
-            }
+            rest_last = 0;
         }

         if (kw_flag & VM_CALL_KW_SPLAT) {
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index c7dd213035..16df7c9fa0 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -1790,12 +1790,6 @@ CALLER_SETUP_ARG(struct rb_control_frame_struct *restrict cfp,
          * So, ci->flag & VM_CALL_ARGS_SPLAT is now inconsistent.
          */
         vm_caller_setup_arg_splat(cfp, calling);
-        if (!IS_ARGS_KW_OR_KW_SPLAT(ci) &&
-                calling->argc > 0 &&
-                RB_TYPE_P(*(cfp->sp - 1), T_HASH) &&
-                (((struct RHash *)*(cfp->sp - 1))->basic.flags & RHASH_PASS_AS_KEYWORDS)) {
-            calling->kw_splat = 1;
-        }
     }
     if (UNLIKELY(IS_ARGS_KEYWORD(ci))) {
         /* This converts VM_CALL_KWARG style to VM_CALL_KW_SPLAT style