diff --git a/build.py b/build.py
index 65bbc87..cf2c740 100644
--- a/build.py
+++ b/build.py
@@ -9,13 +9,23 @@
     return (2000, 1, 1, 1, 1, 1)
 
 
-def clean_zip(path):
+def open_new_file(path):
     path.unlink(missing_ok=True)
+    file = path.open("xb")
+    mode = path.stat().st_mode
+    new_mode = mode | 0o100
+    path.chmod(new_mode)
+    return file
 
 
-def open_zip(path):
+def write_shebang(file):
+    shebang = "#!/usr/bin/env python3\n"
+    file.write(shebang.encode("utf-8"))
+
+
+def open_zip(file):
     return zipfile.ZipFile(
-        path, mode="x", compression=zipfile.ZIP_DEFLATED, compresslevel=9
+        file, mode="a", compression=zipfile.ZIP_DEFLATED, compresslevel=9
     )
 
 
@@ -23,6 +33,10 @@
     zip.close()
 
 
+def close_file(file):
+    file.close()
+
+
 def find_all_src(srcpath):
     paths = srcpath.glob("**/*")
     new_paths = [srcpath]
@@ -69,13 +83,14 @@
 
 
 def main():
-    filename = pathlib.Path("NewLang.pyz")
     date = reproducible_date()
-    clean_zip(filename)
-    zip = open_zip(filename)
+    file = open_new_file(pathlib.Path("NewLang.pyz"))
+    write_shebang(file)
+    zip = open_zip(file)
     write_src(zip, date)
     write_main(zip, date)
     close_zip(zip)
+    close_file(file)
 
 
 if __name__ == "__main__":