diff --git a/spec/lib/mastodon/redis_configuration_spec.rb b/spec/lib/mastodon/redis_configuration_spec.rb
index d8a8dd86d29..560b16ed309 100644
--- a/spec/lib/mastodon/redis_configuration_spec.rb
+++ b/spec/lib/mastodon/redis_configuration_spec.rb
@@ -73,8 +73,6 @@ RSpec.describe Mastodon::RedisConfiguration do
   end
 
   shared_examples 'sentinel support' do |prefix = nil|
-    prefix = prefix ? "#{prefix}_" : ''
-
     context 'when configuring sentinel support' do
       around do |example|
         ClimateControl.modify "#{prefix}REDIS_PASSWORD": 'testpass1', "#{prefix}REDIS_HOST": 'redis2.example.com', "#{prefix}REDIS_SENTINELS": '192.168.0.1:3000,192.168.0.2:4000', "#{prefix}REDIS_SENTINEL_MASTER": 'mainsentinel' do
@@ -199,7 +197,7 @@ RSpec.describe Mastodon::RedisConfiguration do
 
     it_behaves_like 'secondary configuration', 'SIDEKIQ'
     it_behaves_like 'setting a different driver'
-    it_behaves_like 'sentinel support', 'SIDEKIQ'
+    it_behaves_like 'sentinel support', 'SIDEKIQ_'
   end
 
   describe '#cache' do
@@ -225,6 +223,6 @@ RSpec.describe Mastodon::RedisConfiguration do
 
     it_behaves_like 'secondary configuration', 'CACHE'
     it_behaves_like 'setting a different driver'
-    it_behaves_like 'sentinel support', 'CACHE'
+    it_behaves_like 'sentinel support', 'CACHE_'
   end
 end