diff --git a/gaps.py b/gaps.py
old mode 100644
new mode 100755
index a0ebdf0..eb8ab48
--- a/gaps.py
+++ b/gaps.py
@@ -13,7 +13,7 @@ if __name__ == '__main__':
     args = parser.parse_args()
 
     ids = {}
-    files = os.listdir(args.dir)
+    files = os.listdir(args.input)
     for file in files:
         if not file.endswith('.pdf'):
             continue