diff --git a/src/main.py b/src/main.py
index 540ad6e..d21a3be 100644
--- a/src/main.py
+++ b/src/main.py
@@ -52,6 +52,8 @@ def main(files):
 
 
 if __name__ == '__main__':
+    print('WARNING')
+    print('All your sheets should have the same column order.\n')
     ap = argparse.ArgumentParser()
     ap.add_argument('-f', '--files', type=str, nargs='+', help='Files to upload.', required=True)