diff --git a/foliator.py b/foliator.py
index a023108..e09f405 100755
--- a/foliator.py
+++ b/foliator.py
@@ -64,8 +64,17 @@ def blit_to_A4(input_pdf, append_to=PdfWriter()):
         back_page.merge_page(back)
     return writer
 
-input_pdf = PdfReader("to_foliate.pdf")
+parser = argparse.ArgumentParser()
+parser.add_argument("infile",  help="input document, A6 pages")
+parser.add_argument("outfile", help="output document")
+parser.add_argument("-a5", help="output as a5, reverse on short edge",
+                    action="store_true")
+args = parser.parse_args()
+
+input_pdf = PdfReader(args.infile)
 a5 = foliate_A6(input_pdf)
-a5.write("output_A5.pdf")
-a4 = blit_to_A4(a5)
-a4.write("output_A4.pdf")
+if (args.a5):
+    a5.write(args.outfile)
+else:
+    a4 = blit_to_A4(a5)
+    a4.write(args.outfile)