diff --git a/src/html_epub_preprocessor.py b/src/html_epub_preprocessor.py
index 1338ee8..d2c4a33 100644
--- a/src/html_epub_preprocessor.py
+++ b/src/html_epub_preprocessor.py
@@ -95,13 +95,14 @@ def preprocess_table(body_tag: BeautifulSoup):
 
             width = td.get('width') or width
 
-            td.attrs = {}
             if width:
                 td.attrs['width'] = width
 
         if border_sizes:
             border_size = sum(border_sizes) / len(border_sizes)
             table.attrs['border'] = f'{border_size:.2}'
+        else:
+            table.attrs['border'] = '1'
 
 
 def _process_lists(body_tag):