diff --git a/build.py b/build.py
index aecb314..7811d43 100644
--- a/build.py
+++ b/build.py
@@ -51,6 +51,7 @@
 
 def write_zip_entry(zip, name, data, date):
     info = zipfile.ZipInfo(filename=name, date_time=date)
+    info.create_system = 3  # UNIX
     zip.writestr(info, data, compress_type=zipfile.ZIP_DEFLATED, compresslevel=9)