diff --git a/pix2tex/dataset/extract_latex.py b/pix2tex/dataset/extract_latex.py
index d80b26c..66f6035 100644
--- a/pix2tex/dataset/extract_latex.py
+++ b/pix2tex/dataset/extract_latex.py
@@ -2,7 +2,6 @@
 import html
 import os
 import re
-import numpy as np
 from typing import List
 
 MIN_CHARS = 1
@@ -33,8 +32,8 @@ def check_brackets(s):
                 continue
             else:
                 a.append(-1)
-    b = np.cumsum(a)
-    if len(b) > 1 and b[-1] != 0:
+    b = sum(a)
+    if len(a) > 1 and b != 0:
         raise ValueError(s)
     surrounding = s[-1] == '}' and surrounding
     if not surrounding:
@@ -120,4 +119,4 @@ def find_math(s: str, wiki=False) -> List[str]:
     else:
         with open(args.out, 'w') as f:
             f.write(math)
-    
\ No newline at end of file
+