diff --git a/test/ruby/test_keyword.rb b/test/ruby/test_keyword.rb
index 2061b49e45..9425e1df5d 100644
--- a/test/ruby/test_keyword.rb
+++ b/test/ruby/test_keyword.rb
@@ -681,12 +681,13 @@ class TestKeywordArguments < Test::Unit::TestCase
   def many_kwargs(a0: '', a1: '', a2: '', a3: '', a4: '', a5: '', a6: '', a7: '',
                   b0: '', b1: '', b2: '', b3: '', b4: '', b5: '', b6: '', b7: '',
                   c0: '', c1: '', c2: '', c3: '', c4: '', c5: '', c6: '', c7: '',
-                  d0: '', d1: '', d2: '', d3: '', d4: '', d5: '', d6: '', d7: '')
+                  d0: '', d1: '', d2: '', d3: '', d4: '', d5: '', d6: '', d7: '',
+                  e0: '')
     [a0, a1, a2, a3, a4, a5, a6, a7,
      b0, b1, b2, b3, b4, b5, b6, b7,
      c0, c1, c2, c3, c4, c5, c6, c7,
      d0, d1, d2, d3, d4, d5, d6, d7,
-    ]
+     e0]
   end
 
   def test_many_kwargs
@@ -726,5 +727,7 @@ class TestKeywordArguments < Test::Unit::TestCase
     assert_equal(:ok, many_kwargs(d5: :ok)[i], "#{i}: d5"); i+=1
     assert_equal(:ok, many_kwargs(d6: :ok)[i], "#{i}: d6"); i+=1
     assert_equal(:ok, many_kwargs(d7: :ok)[i], "#{i}: d7"); i+=1
+
+    assert_equal(:ok, many_kwargs(e0: :ok)[i], "#{i}: e0"); i+=1
   end
 end
diff --git a/vm_args.c b/vm_args.c
index c61f50d933..c1d829c019 100644
--- a/vm_args.c
+++ b/vm_args.c
@@ -392,6 +392,8 @@ args_setup_kw_parameters_lookup(const ID key, VALUE *ptr, const VALUE *const pas
     return FALSE;
 }
 
+#define KW_SPECIFIED_BITS_MAX 32 /* TODO: 32 -> Fixnum's max bits */
+
 static void
 args_setup_kw_parameters(rb_execution_context_t *const ec, const rb_iseq_t *const iseq,
 			 VALUE *const passed_values, const int passed_keyword_len, const VALUE *const passed_keywords,
@@ -427,7 +429,7 @@ args_setup_kw_parameters(rb_execution_context_t *const ec, const rb_iseq_t *cons
 	    if (default_values[di] == Qundef) {
 		locals[i] = Qnil;
 
-		if (LIKELY(i < 32)) { /* TODO: 32 -> Fixnum's max bits */
+		if (LIKELY(i < KW_SPECIFIED_BITS_MAX)) {
 		    unspecified_bits |= 0x01 << di;
 		}
 		else {
@@ -436,7 +438,7 @@ args_setup_kw_parameters(rb_execution_context_t *const ec, const rb_iseq_t *cons
 			int j;
 			unspecified_bits_value = rb_hash_new();
 
-			for (j=0; j<32; j++) {
+			for (j=0; j<KW_SPECIFIED_BITS_MAX; j++) {
 			    if (unspecified_bits & (0x01 << j)) {
 				rb_hash_aset(unspecified_bits_value, INT2FIX(j), Qtrue);
 			    }
diff --git a/vm_insnhelper.c b/vm_insnhelper.c
index e18235da57..64ac539523 100644
--- a/vm_insnhelper.c
+++ b/vm_insnhelper.c
@@ -3029,7 +3029,8 @@ vm_check_keyword(lindex_t bits, lindex_t idx, const VALUE *ep)
 
     if (FIXNUM_P(kw_bits)) {
 	int b = FIX2INT(kw_bits);
-	if (b & (0x01 << idx)) return Qfalse;
+	if ((idx < KW_SPECIFIED_BITS_MAX) && (b & (0x01 << idx)))
+	    return Qfalse;
     }
     else {
 	VM_ASSERT(RB_TYPE_P(kw_bits, T_HASH));