diff --git a/ruby/lib/ci/queue/redis/base.rb b/ruby/lib/ci/queue/redis/base.rb
index 025134a9..110bf01e 100644
--- a/ruby/lib/ci/queue/redis/base.rb
+++ b/ruby/lib/ci/queue/redis/base.rb
@@ -92,7 +92,7 @@ def stop_heartbeat!
         end
 
         def custom_config
-          return unless config.debug_log
+          return {} unless config.debug_log
 
           require 'logger'
           { debug_log: Logger.new(config.debug_log) }
diff --git a/ruby/test/ci/queue/redis_test.rb b/ruby/test/ci/queue/redis_test.rb
index e518f538..1f2c6815 100644
--- a/ruby/test/ci/queue/redis_test.rb
+++ b/ruby/test/ci/queue/redis_test.rb
@@ -270,6 +270,18 @@ def test_initialise_from_rediss_uri
     assert_instance_of CI::Queue::Redis::Worker, queue
   end
 
+  def test_custom_config_returns_empty_hash_by_default
+    queue = worker(1)
+    custom_config = queue.send(:custom_config)
+    assert_equal({}, custom_config)
+  end
+
+  def test_custom_config_returns_logger_when_debug_log_is_set
+    queue = worker(1, debug_log: '/dev/null')
+    custom_config = queue.send(:custom_config)
+    assert_kind_of Logger, custom_config[:debug_log]
+  end
+
   private
 
   def shuffled_test_list