diff --git a/generate_errors.py b/generate_errors.py
index 7272f0c..d189f7d 100644
--- a/generate_errors.py
+++ b/generate_errors.py
@@ -32,9 +32,10 @@ nginx_body = ''
 
 for item in codes:
     code, title, desc = item.groups()
-    if int(code) < 300 or int(code) >= 600: continue
+    if int(code) < 400 or int(code) >= 600: continue
     with error.joinpath(f'{code}.html').open('w') as html:
-        html.write(root_html.format(code=code, title=title, desc=desc, style=root_css))
+        html.write(root_html.format(
+            code=code, title=title, desc=desc, style=root_css))
     nginx_head += f'error_page {code} @error{code};\n'
     nginx_body += f'location @error{code} {{\n'\
         f'root {error.resolve()};\n'\