diff --git a/gen_pack.py b/gen_pack.py
index 7782655..f82d5fc 100644
--- a/gen_pack.py
+++ b/gen_pack.py
@@ -168,7 +168,7 @@ def zipdir(path, ziph):
                                        os.path.join(path, '..')))
 
 def makeZip(filename):
-    with zipfile.ZipFile(filename, 'w', zipfile.ZIP_DEFLATED) as zipf:
+    with zipfile.ZipFile(filename, 'w', zipfile.ZIP_DEFLATED, compresslevel=9) as zipf:
         zipdir('assets/', zipf)
         zipf.write('pack.mcmeta')
         zipf.write('pack.png')