diff --git a/changelog.md b/changelog.md
index 32a01b3b..ca86e504 100644
--- a/changelog.md
+++ b/changelog.md
@@ -11,6 +11,8 @@ Removed features:
 
 Internal improvements:
 
+ * explicitly require ostruct for ruby >= 3.3.5 ([694](https://github.com/arsduo/koala/pull/694))
+
 Testing improvements:
 
 Others:
diff --git a/koala.gemspec b/koala.gemspec
index 5c16e6f1..56058666 100644
--- a/koala.gemspec
+++ b/koala.gemspec
@@ -29,4 +29,5 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency("json", ">= 1.8")
   gem.add_runtime_dependency("rexml")
   gem.add_runtime_dependency("base64")
+  gem.add_runtime_dependency("ostruct")
 end