diff --git a/test/ruby/test_proc.rb b/test/ruby/test_proc.rb
index af4cf11623..4177707ddd 100644
--- a/test/ruby/test_proc.rb
+++ b/test/ruby/test_proc.rb
@@ -1087,6 +1087,26 @@ class TestProc < Test::Unit::TestCase
     assert_equal([1,2,[3],4,5], r, "[ruby-core:19485]")
   end
 
+  def test_proc_autosplat
+    def self.a(arg, kw)
+      yield arg
+      yield arg, **kw
+      yield arg, kw
+    end
+
+    arr = []
+    a([1,2,3], {}) do |arg1, arg2=0|
+      arr << [arg1, arg2]
+    end
+    assert_equal([[1, 2], [[1, 2, 3], 0], [[1, 2, 3], {}]], arr)
+
+    arr = []
+    a([1,2,3], a: 1) do |arg1, arg2=0|
+      arr << [arg1, arg2]
+    end
+    assert_equal([[1, 2], [[1, 2, 3], {a: 1}], [[1, 2, 3], {a: 1}]], arr)
+  end
+
   def test_proc_single_arg_with_keywords_accepted_and_yielded
     def self.a
       yield [], **{a: 1}
diff --git a/vm_args.c b/vm_args.c
index 256ab5b7f4..13d4e4a545 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -445,9 +445,9 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
 {
     const int min_argc = iseq->body->param.lead_num + iseq->body->param.post_num;
     const int max_argc = (iseq->body->param.flags.has_rest == FALSE) ? min_argc + iseq->body->param.opt_num : UNLIMITED_ARGUMENTS;
-    int opt_pc = 0;
     int given_argc;
     unsigned int kw_flag = ci->flag & (VM_CALL_KWARG | VM_CALL_KW_SPLAT);
+    int opt_pc = 0, allow_autosplat = !kw_flag;
     struct args_info args_body, *args;
     VALUE keyword_hash = Qnil;
     VALUE * const orig_sp = ec->cfp->sp;
@@ -573,6 +573,7 @@ setup_parameters_complex(rb_execution_context_t * const ec, const rb_iseq_t * co
 	break; /* do nothing special */
       case arg_setup_block:
         if (given_argc == (keyword_hash == Qnil ? 1 : 2) &&
+            allow_autosplat &&
 	    (min_argc > 0 || iseq->body->param.opt_num > 1 ||
 	     iseq->body->param.flags.has_kw || iseq->body->param.flags.has_kwrest) &&
 	    !iseq->body->param.flags.ambiguous_param0 &&