diff --git a/app/finders/issues_finder.rb b/app/finders/issues_finder.rb
index 08713272947..76715e5970d 100644
--- a/app/finders/issues_finder.rb
+++ b/app/finders/issues_finder.rb
@@ -9,7 +9,7 @@
 #     state: 'open' or 'closed' or 'all'
 #     group_id: integer
 #     project_id: integer
-#     milestone_id: integer
+#     milestone_title: string
 #     assignee_id: integer
 #     search: string
 #     label_name: string
diff --git a/app/finders/merge_requests_finder.rb b/app/finders/merge_requests_finder.rb
index 1eec45d9cb5..42f0ebd774c 100644
--- a/app/finders/merge_requests_finder.rb
+++ b/app/finders/merge_requests_finder.rb
@@ -9,7 +9,7 @@
 #     state: 'open' or 'closed' or 'all'
 #     group_id: integer
 #     project_id: integer
-#     milestone_id: integer
+#     milestone_title: string
 #     assignee_id: integer
 #     search: string
 #     label_name: string
diff --git a/changelogs/unreleased/bug-api_milestone_merge_requests_scope.yml b/changelogs/unreleased/bug-api_milestone_merge_requests_scope.yml
new file mode 100644
index 00000000000..a1e1c29165e
--- /dev/null
+++ b/changelogs/unreleased/bug-api_milestone_merge_requests_scope.yml
@@ -0,0 +1,4 @@
+---
+title: Fixes milestone/merge_requests endpoint to actually scope the result
+merge_request:
+author: Joren De Groof
diff --git a/lib/api/milestones.rb b/lib/api/milestones.rb
index e7ab82f08db..a3ea619a2fb 100644
--- a/lib/api/milestones.rb
+++ b/lib/api/milestones.rb
@@ -139,7 +139,7 @@ module API
 
         finder_params = {
           project_id: user_project.id,
-          milestone_id: milestone.id,
+          milestone_title: milestone.title,
           sort: 'position_asc'
         }
 
diff --git a/spec/requests/api/milestones_spec.rb b/spec/requests/api/milestones_spec.rb
index 7fb728fed6f..598968aff70 100644
--- a/spec/requests/api/milestones_spec.rb
+++ b/spec/requests/api/milestones_spec.rb
@@ -306,6 +306,8 @@ describe API::Milestones, api: true  do
     end
 
     it 'returns project merge_requests for a particular milestone' do
+      # eager-load another_merge_request
+      another_merge_request
       get api("/projects/#{project.id}/milestones/#{milestone.id}/merge_requests", user)
 
       expect(response).to have_http_status(200)