diff --git a/launch_parser_on_nidm.py b/launch_parser_on_nidm.py
index 5981f889f..8596dbfc2 100755
--- a/launch_parser_on_nidm.py
+++ b/launch_parser_on_nidm.py
@@ -81,8 +81,8 @@ def main():
     context_write.write("Processing files...\n")
 
     # Iteration on each example
-    for root, _, files in os.walk(opt.input_dir):
-        for file in files:
+    for root, _, files in sorted(os.walk(opt.input_dir)):
+        for file in sorted(files):
 
             if file.endswith("batch.m"):  # spm
                 filename_ss_ext = file.split(".m")[0]