diff --git a/examples/rdkafka/producer.rb b/examples/rdkafka/producer.rb
index 522a17c..b50c1ce 100644
--- a/examples/rdkafka/producer.rb
+++ b/examples/rdkafka/producer.rb
@@ -4,18 +4,18 @@
 require_relative "oauth_token_refresher"
 
 module Producer
-  CLIENTS = {}.freeze
+  @clients = {}
 
   def self.from_name(client_name)
-    raise "Client not found: #{client_name}\n" if CLIENTS[client_name].nil?
+    raise "Client not found: #{client_name}\n" if @clients[client_name].nil?
 
-    CLIENTS[client_name]
+    @clients[client_name]
   end
 
   def self.start!(kafka_config)
     Rdkafka::Config.oauthbearer_token_refresh_callback = method(:refresh_token)
     @producer = Rdkafka::Config.new(kafka_config).producer(native_kafka_auto_start: false)
-    CLIENTS[@producer.name] = @producer
+    @clients[@producer.name] = @producer
     @producer.start
   end