diff --git a/CHANGELOG.md b/CHANGELOG.md
index 317d6c6410..b27e57aecb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,11 +1,13 @@
 # Changelog
 
 ## v4.1.1
-- Updated fontawesome to V6
+
 ### Added
 - Added `MORE_INFO` and `LESS_INFO` JS constants (for the Research Outputs feature)
 ### Fixed
 - Updated the default font on the 'Download page' to be 'Roboto, Arial, Sans-Serif'
+- Fixed an issue with API V0 that was causing a 500 Internal Server error
+- Updated fontawesome to V6
 
 
 ## v4.1.0
diff --git a/app/controllers/api/v0/plans_controller.rb b/app/controllers/api/v0/plans_controller.rb
index 4e74ab2db9..4f61a211d3 100644
--- a/app/controllers/api/v0/plans_controller.rb
+++ b/app/controllers/api/v0/plans_controller.rb
@@ -101,7 +101,7 @@ def index
         max_per_page = Rails.configuration.x.application.api_max_page_size
         page = params.fetch('page', 1).to_i
         per_page = params.fetch('per_page', max_per_page).to_i
-        per_page = max_per_page if @per_page > max_per_page
+        per_page = max_per_page if per_page > max_per_page
         @args = { per_page: per_page, page: page }
         @plans = refine_query(@plans)
         respond_with @plans