diff --git a/quartz/components/scripts/explorer.inline.ts b/quartz/components/scripts/explorer.inline.ts
index e98b2035e..8d401ad58 100644
--- a/quartz/components/scripts/explorer.inline.ts
+++ b/quartz/components/scripts/explorer.inline.ts
@@ -7,7 +7,7 @@ type MaybeHTMLElement = HTMLElement | undefined
 interface ParsedOptions {
   folderClickBehavior: "collapse" | "link"
   folderDefaultState: "collapsed" | "open"
-  maxExpandLevel?: number
+  maxExpandLevel: number
   useSavedState: boolean
   sortFn: (a: FileTrieNode, b: FileTrieNode) => number
   filterFn: (node: FileTrieNode) => boolean