diff --git a/overwrought_master.py b/overwrought_master.py
index 9ce2f6f..3add1c8 100755
--- a/overwrought_master.py
+++ b/overwrought_master.py
@@ -201,7 +201,12 @@ def update_mod(target, delete=False, phase=None):
 		download_mod(mod_latest)
 		mod_latest.save()
 		log_change(f"Updated {mod_latest.title} to {mod_latest.filename}")
-		if delete:
+		if not delete:
+			os.makedirs("mods_old", exist_ok=True)
+			os.rename(os.path.join("mods", mod_current.filename),
+				os.path.join("mods_old", mod_current.filename)
+			)
+		else:
 			os.remove(os.path.join("mods", mod_current.filename))