diff --git a/magic_spoiler/__main__.py b/magic_spoiler/__main__.py
index 50372000..05ec5ac4 100644
--- a/magic_spoiler/__main__.py
+++ b/magic_spoiler/__main__.py
@@ -203,8 +203,8 @@ def open_header(card_xml_file: IO[Any]) -> None:
     :param card_xml_file: Card file path
     """
     card_xml_file.write(
-        "<?xml version="1.0" encoding="UTF-8"?>\n"
-        + "<cockatrice_carddatabase version='4' xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://raw.githubusercontent.com/Cockatrice/Cockatrice/master/doc/carddatabase_v3/cards.xsd">\n"
+        "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
+        + "<cockatrice_carddatabase version=\"4\" xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xsi:schemaLocation=\"https://raw.githubusercontent.com/Cockatrice/Cockatrice/master/doc/carddatabase_v3/cards.xsd\">\n"
         + "  <!--\n"
         + "  THIS FILE IS AUTOMATICALLY GENERATED & ALL EDITS WILL BE OVERRIDDEN.\n"
         + "  -->\n"