diff --git a/slideslurp/__init__.py b/slideslurp/__init__.py
index d76d8a7..c98e58f 100644
--- a/slideslurp/__init__.py
+++ b/slideslurp/__init__.py
@@ -3,6 +3,7 @@ import sys
 
 import bs4
 import requests
+from urllib.parse import urlparse
 
 from reportlab.pdfgen import canvas
 
@@ -13,11 +14,14 @@ def parse_args():
     parser = argparse.ArgumentParser(description=descr)
     parser.add_argument('url', metavar='url', nargs=1,
                         help='the URL to slurp')
-    parser.add_argument('--output', '-o', default='out.pdf',
+    parser.add_argument('--output', '-o',  default=None,
                         help='the file to write to (default: out.pdf)')
 
-    return parser.parse_args()
-
+    args = parser.parse_args()
+    if not args.output:
+        path = urlparse(args.url[0]).path
+        args.output = '%s.pdf'%path[path.find('/', 1) + 1:]
+    return args
 
 def main():
     args = parse_args()
@@ -31,7 +35,8 @@ def main():
         img_url = img.attrs["data-full"]
         page_width, page_height = c._pagesize
         c.setPageRotation(90)
-        c.drawImage(img_url, 0, 0, page_height, page_width, preserveAspectRatio=True)
+        c.drawImage(img_url, 0, 0, page_height, page_width,
+                    preserveAspectRatio=True)
         c.showPage()
     c.save()