diff --git a/README.md b/README.md
index 3afaea7c998259d2a5f8a3ea2fc7b072301ef902..7d99231b32318cad535777ddcbc3f84e92491dc6 100644
--- a/README.md
+++ b/README.md
@@ -15,7 +15,7 @@ Extraire les notes d'une liseuse Vivlio
 optional arguments:
   -h, --help            show this help message and exit
   -s SOURCE, --source SOURCE
-                        le dossier de la liseuse
+                        le dossier de la liseuse (optional for linux, mandatory for other OSes)
   -f FORMAT, --format FORMAT
                         le format d'export (JSON ou wiki)
   -d DESTINATION, --destination DESTINATION
diff --git a/extract_notes.py b/extract_notes.py
index 286800bed4558499cf612dfc71bccd42949d2dee..b456cf1e1efe3f23232bda0a46e405a18325e87b 100755
--- a/extract_notes.py
+++ b/extract_notes.py
@@ -233,7 +233,7 @@ def export_data(data, directory, format="json"):
 				curbook.empty()
 			curbook = Book(comment[1],comment[0])
 		curbook.addNote(Note(comment[3],comment[2]))
-	if curbook.is_empty():
+	if not curbook.is_empty():
 		curbook.store(directory, format)
 
 #main