diff --git a/test/reline/test_key_actor_emacs.rb b/test/reline/test_key_actor_emacs.rb
index 5ace062cc2..fb879e5fcd 100644
--- a/test/reline/test_key_actor_emacs.rb
+++ b/test/reline/test_key_actor_emacs.rb
@@ -2306,6 +2306,22 @@ def test_ed_argument_digit_by_meta_num
     assert_line('abcd')
   end
 
+  def test_halfwidth_kana_width_dakuten
+    input_keys('ｶﾞｷﾞｹﾞｺﾞ')
+    assert_byte_pointer_size('ｶﾞｷﾞｹﾞｺﾞ')
+    assert_cursor(8)
+    assert_cursor_max(8)
+    input_keys("\C-b\C-b", false)
+    assert_byte_pointer_size('ｶﾞｷﾞ')
+    assert_cursor(4)
+    assert_cursor_max(8)
+    input_keys('ｸﾞ', false)
+    assert_byte_pointer_size('ｶﾞｷﾞｸﾞ')
+    assert_cursor(6)
+    assert_cursor_max(10)
+    assert_line('ｶﾞｷﾞｸﾞｹﾞｺﾞ')
+  end
+
   def test_input_unknown_char
     input_keys('͸') # U+0378 (unassigned)
     assert_line('͸')