diff --git a/module/ocr/keyword.py b/module/ocr/keyword.py
index 5b8ad91..2452ab4 100644
--- a/module/ocr/keyword.py
+++ b/module/ocr/keyword.py
@@ -201,3 +201,18 @@ class Keyword:
 
         # Not found
         raise ScriptError(f'Cannot find a {cls.__name__} instance that matches "{name}"')
+
+
+class KeywordDigitCounter(Keyword):
+    """
+    A fake Keyword class to filter digit counters in ocr results
+    OcrResultButton.match_keyword will be a str
+    """
+
+    @classmethod
+    def find(cls, name, lang: str = None, ignore_punctuation=True):
+        from module.ocr.ocr import DigitCounter
+        if DigitCounter.is_format_matched(name):
+            return name
+        else:
+            raise ScriptError
diff --git a/module/ocr/ocr.py b/module/ocr/ocr.py
index a099d26..82fb32d 100644
--- a/module/ocr/ocr.py
+++ b/module/ocr/ocr.py
@@ -1,7 +1,6 @@
 import re
 import time
 from datetime import timedelta
-from typing import Optional
 
 import cv2
 import numpy as np
@@ -13,13 +12,12 @@ from module.base.decorator import cached_property
 from module.base.utils import area_pad, corner2area, crop, extract_white_letters, float2str
 from module.exception import ScriptError
 from module.logger import logger
-from module.ocr.keyword import Keyword
 from module.ocr.models import OCR_MODEL, TextSystem
 from module.ocr.utils import merge_buttons
 
 
 class OcrResultButton:
-    def __init__(self, boxed_result: BoxedResult, matched_keyword: Optional[Keyword]):
+    def __init__(self, boxed_result: BoxedResult, matched_keyword):
         """
         Args:
             boxed_result: BoxedResult from ppocr-onnx
diff --git a/module/ocr/utils.py b/module/ocr/utils.py
index 357836f..d7a1584 100644
--- a/module/ocr/utils.py
+++ b/module/ocr/utils.py
@@ -74,8 +74,8 @@ def pair_buttons(group1, group2, relative_area):
     Pair buttons in group1 with those in group2 in the relative_area.
 
     Args:
-        group1 (list[OcrResultButton]):
-        group2 (list[OcrResultButton]):
+        group1 (list[OcrResultButton], Iterable[OcrResultButton]):
+        group2 (list[OcrResultButton], Iterable[OcrResultButton]):
         relative_area (tuple[int, int, int, int]):
 
     Yields: