diff --git a/main.py b/main.py
index 84715c6..a538683 100644
--- a/main.py
+++ b/main.py
@@ -6,12 +6,15 @@ from bs4 import BeautifulSoup
 if __name__ == '__main__':
     parser = argparse.ArgumentParser(description="Dig out links from a website.")
     parser.add_argument('site', type=str, help="Website that you want to scrape for links.")
+    parser.add_argument('-f', '--filter', type=str, default='\..*$', help="Only return filenames matching this regular expression.")
     args = parser.parse_args()
     
     h = httplib2.Http('.cache')
     response, content = h.request(args.site)
     s = BeautifulSoup(content)
     """find only file names"""
-    links = s.find_all(href=re.compile('\..*$'))
+    links = s.find_all(href=re.compile(args.filter))
+    if not links or links == 0:
+        exit("No filenames found with the given filter.")
     for link in links:
         print(args.site + link['href'])