diff --git a/swash/processing/swash.py b/swash/processing/swash.py
index c47aadb..13c389f 100644
--- a/swash/processing/swash.py
+++ b/swash/processing/swash.py
@@ -66,4 +66,8 @@ with tempfile.TemporaryDirectory(prefix="swash_", dir=".") as tmp_raw:
     log.info(f"Moving swash output to '{out}'")
     shutil.move(tmpdir, out)
 
+for f in out.rglob("*"):
+    if f.is_file():
+        f.chmod(0o444)
+
 log.info(f"Swash model finished successfully")