diff --git a/CHANGELOG.md b/CHANGELOG.md
index d5648e8..e513069 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- Bugfix ensuring aliases value is array when treated as one
+
 ## [1.0.5]
 
 - Change to use `url` instead of `inputPath` for unique page key, this is because some pages can share the same `inputPath` such as those generated via pagination.
diff --git a/index.js b/index.js
index af94684..b04fa5d 100644
--- a/index.js
+++ b/index.js
@@ -144,7 +144,7 @@ module.exports = function (eleventyConfig, options = {}) {
               const found = (page.fileSlug === link.slug || (page.data.title && opts.slugifyFn(page.data.title) === link.slug));
               if (found) return true;
 
-              const aliases = (page.data.aliases ?? []).reduce(function(set, alias){
+              const aliases = ((page.data.aliases && Array.isArray(page.data.aliases)) ? page.data.aliases : []).reduce(function(set, alias){
                 set.add(opts.slugifyFn(alias));
                 return set;
               }, new Set());