diff --git a/lib/api/entities/commit_detail.rb b/lib/api/entities/commit_detail.rb
index 428c53f7fe39837b1914e847c0c25d6e57addae4..f685f6fefa961b92c6cfa83bb8c5e2ee530fd1c8 100644
--- a/lib/api/entities/commit_detail.rb
+++ b/lib/api/entities/commit_detail.rb
@@ -9,7 +9,7 @@ class CommitDetail < Commit
       expose :status_for, as: :status, documentation: { type: 'string', example: 'success' }
       expose :project_id, documentation: { type: 'integer', example: 1 }
 
-      expose :last_pipeline, documentation: { type: ::API::Entities::Ci::PipelineBasic.to_s } do |commit, options|
+      expose :last_pipeline, using: ::API::Entities::Ci::PipelineBasic do |commit, options|
         pipeline = commit.last_pipeline if can_read_pipeline?
         ::API::Entities::Ci::PipelineBasic.represent(pipeline, options)
       end