diff --git a/app/controllers/api/v1/accounts/familiar_followers_controller.rb b/app/controllers/api/v1/accounts/familiar_followers_controller.rb
index b0bd8018a21..a49eb2eb274 100644
--- a/app/controllers/api/v1/accounts/familiar_followers_controller.rb
+++ b/app/controllers/api/v1/accounts/familiar_followers_controller.rb
@@ -12,7 +12,7 @@ class Api::V1::Accounts::FamiliarFollowersController < Api::BaseController
   private
 
   def set_accounts
-    @accounts = Account.without_suspended.where(id: account_ids).select('id, hide_collections').index_by(&:id).values_at(*account_ids).compact
+    @accounts = Account.without_suspended.where(id: account_ids).select('id, hide_collections')
   end
 
   def familiar_followers
diff --git a/app/controllers/api/v1/accounts/relationships_controller.rb b/app/controllers/api/v1/accounts/relationships_controller.rb
index 320084efb5c..e5ae5b007ba 100644
--- a/app/controllers/api/v1/accounts/relationships_controller.rb
+++ b/app/controllers/api/v1/accounts/relationships_controller.rb
@@ -5,11 +5,8 @@ class Api::V1::Accounts::RelationshipsController < Api::BaseController
   before_action :require_user!
 
   def index
-    scope = Account.where(id: account_ids).select('id')
-    scope.merge!(Account.without_suspended) unless truthy_param?(:with_suspended)
-    # .where doesn't guarantee that our results are in the same order
-    # we requested them, so return the "right" order to the requestor.
-    @accounts = scope.index_by(&:id).values_at(*account_ids).compact
+    @accounts = Account.where(id: account_ids).select('id')
+    @accounts.merge!(Account.without_suspended) unless truthy_param?(:with_suspended)
     render json: @accounts, each_serializer: REST::RelationshipSerializer, relationships: relationships
   end
 
diff --git a/spec/controllers/api/v1/accounts/familiar_followers_controller_spec.rb b/spec/controllers/api/v1/accounts/familiar_followers_controller_spec.rb
index bb075261f3a..22617730945 100644
--- a/spec/controllers/api/v1/accounts/familiar_followers_controller_spec.rb
+++ b/spec/controllers/api/v1/accounts/familiar_followers_controller_spec.rb
@@ -19,5 +19,17 @@ describe Api::V1::Accounts::FamiliarFollowersController do
 
       expect(response).to have_http_status(200)
     end
+
+    context 'when there are duplicate account IDs in the params' do
+      let(:account_a) { Fabricate(:account) }
+      let(:account_b) { Fabricate(:account) }
+
+      it 'removes duplicate account IDs from params' do
+        account_ids = [account_a, account_b, account_b, account_a, account_a].map { |a| a.id.to_s }
+        get :index, params: { id: account_ids }
+
+        expect(body_as_json.pluck(:id)).to eq [account_a.id.to_s, account_b.id.to_s]
+      end
+    end
   end
 end
diff --git a/spec/requests/api/v1/accounts/relationships_spec.rb b/spec/requests/api/v1/accounts/relationships_spec.rb
index e06ffdfae97..cea45168a21 100644
--- a/spec/requests/api/v1/accounts/relationships_spec.rb
+++ b/spec/requests/api/v1/accounts/relationships_spec.rb
@@ -79,6 +79,22 @@ describe 'GET /api/v1/accounts/relationships' do
         end
       end
 
+      context 'when there are duplicate IDs in the params' do
+        let(:params) { { id: [simon.id, lewis.id, lewis.id, lewis.id, simon.id] } }
+
+        it 'removes duplicate account IDs from params' do
+          subject
+
+          expect(body_as_json)
+            .to be_an(Enumerable)
+            .and have_attributes(
+              size: 2,
+              first: include(simon_item),
+              second: include(lewis_item)
+            )
+        end
+      end
+
       def simon_item
         {
           id: simon.id.to_s,