diff --git a/mmocr/models/textrecog/dictionary/dictionary.py b/mmocr/models/textrecog/dictionary/dictionary.py
index cb3916a0..d16dc875 100644
--- a/mmocr/models/textrecog/dictionary/dictionary.py
+++ b/mmocr/models/textrecog/dictionary/dictionary.py
@@ -1,6 +1,5 @@
 # Copyright (c) OpenMMLab. All rights reserved.
-import re
-from typing import List, Optional, Sequence
+from typing import List, Sequence
 
 from mmocr.registry import TASK_UTILS
 from mmocr.utils import list_from_file
@@ -50,8 +49,7 @@ class Dictionary:
                  end_token: str = '<EOS>',
                  start_end_token: str = '<BOS/EOS>',
                  padding_token: str = '<PAD>',
-                 unknown_token: Optional[str] = '<UKN>',
-                 **kwargs) -> None:
+                 unknown_token: str = '<UKN>') -> None:
         self.with_start = with_start
         self.with_end = with_end
         self.same_start_end = same_start_end
@@ -75,10 +73,8 @@ class Dictionary:
                 self._dict.append(line)
 
         self._char2idx = {char: idx for idx, char in enumerate(self._dict)}
-        self._contain_uppercase = len(re.findall('[A-Z]', ''.join(
-            self.dict))) > 0
 
-        self._update_dict(**kwargs)
+        self._update_dict()
         assert len(set(self._dict)) == len(self._dict), \
             'Invalid dictionary: Has duplicated characters.'
 
@@ -90,16 +86,10 @@ class Dictionary:
 
     @property
     def dict(self) -> list:
-        """list: The list of all character to recognize, which Special tokens
-        are counted."""
+        """list: Returns a list of characters to recognize, where special
+        tokens are counted."""
         return self._dict
 
-    @property
-    def contain_uppercase(self) -> bool:
-        """bool: Whether all the English characters in dict file are in lowercase.
-        """
-        return self._contain_uppercase
-
     def char2idx(self, char: str, strict: bool = True) -> int:
         """Convert a character to an index via ``Dictionary.dict``.
 
@@ -158,10 +148,12 @@ class Dictionary:
         assert isinstance(index, (list, tuple))
         string = ''
         for i in index:
+            assert i < len(self._dict), f'Index: {i} out of range! Index ' \
+                                        f'must be less than {len(self._dict)}'
             string += self._dict[i]
         return string
 
-    def _update_dict(self, **kwargs):
+    def _update_dict(self):
         """Update the dict with tokens according to parameters."""
         # BOS/EOS
         self.start_idx = None
diff --git a/tests/test_models/test_kie/test_heads/test_sdmgr_head.py b/tests/test_models/test_kie/test_heads/test_sdmgr_head.py
index 7f83d57d..6c1efc3d 100644
--- a/tests/test_models/test_kie/test_heads/test_sdmgr_head.py
+++ b/tests/test_models/test_kie/test_heads/test_sdmgr_head.py
@@ -40,6 +40,7 @@ class TestSDMGRHead(TestCase):
             self.assertEqual(edge_cls.shape, torch.Size([4, 2]))
 
             # When input image is None
+            del (dict_cfg['type'])
             head = SDMGRHead(dictionary=Dictionary(**dict_cfg))
             node_cls, edge_cls = head(None, [data_sample])
             self.assertEqual(node_cls.shape, torch.Size([2, 26]))
diff --git a/tests/test_models/test_textrecog/test_dictionary/test_dictionary.py b/tests/test_models/test_textrecog/test_dictionary/test_dictionary.py
index 03827d20..df3a022d 100644
--- a/tests/test_models/test_textrecog/test_dictionary/test_dictionary.py
+++ b/tests/test_models/test_textrecog/test_dictionary/test_dictionary.py
@@ -89,17 +89,6 @@ class TestDictionary(TestCase):
             dict_gen = Dictionary(dict_file=dict_file)
             assert dict_gen.num_classes == 36
 
-    def test_contain_uppercase(self):
-        with tempfile.TemporaryDirectory() as tmp_dir:
-            # create dummy data
-            dict_file = osp.join(tmp_dir, 'fake_chars.txt')
-            create_dummy_dict_file(dict_file)
-            dict_gen = Dictionary(dict_file=dict_file)
-            assert dict_gen.contain_uppercase is False
-            create_dummy_dict_file(dict_file, chars='abcdABCD')
-            dict_gen = Dictionary(dict_file=dict_file)
-            assert dict_gen.contain_uppercase is True
-
     def test_char2idx(self):
         with tempfile.TemporaryDirectory() as tmp_dir:
 
@@ -150,3 +139,5 @@ class TestDictionary(TestCase):
             self.assertEqual(dict_gen.idx2str([0, 1, 2, 3, 4]), '01234')
             with self.assertRaises(AssertionError):
                 dict_gen.idx2str('01234')
+            with self.assertRaises(AssertionError):
+                dict_gen.idx2str([40])
diff --git a/tests/test_models/test_textrecog/test_postprocessors/test_base_textrecog_postprocessor.py b/tests/test_models/test_textrecog/test_postprocessors/test_base_textrecog_postprocessor.py
index 0426f0a2..a4918b46 100644
--- a/tests/test_models/test_textrecog/test_postprocessors/test_base_textrecog_postprocessor.py
+++ b/tests/test_models/test_textrecog/test_postprocessors/test_base_textrecog_postprocessor.py
@@ -87,7 +87,7 @@ class TestBaseTextRecogPostprocessor(TestCase):
                     type='Dictionary',
                     dict_file=dict_file,
                     with_unknown=True,
-                    unkown_token=None),
+                    unknown_token=None),
                 ignore_chars=['M'])
 
         with self.assertWarnsRegex(Warning,