diff --git a/tools/doc/generate.js b/tools/doc/generate.js
index f49acb6207c9b4..d2f3aea27f25a4 100644
--- a/tools/doc/generate.js
+++ b/tools/doc/generate.js
@@ -43,7 +43,7 @@ let filename = null;
 let nodeVersion = null;
 let outputDir = null;
 let apilinks = {};
-let versions = {};
+let versions = [];
 
 async function main() {
   for (const arg of args) {