diff --git a/lib/prome/sidekiq.rb b/lib/prome/sidekiq.rb
index e46a1e5..acf2b56 100644
--- a/lib/prome/sidekiq.rb
+++ b/lib/prome/sidekiq.rb
@@ -11,7 +11,7 @@ def self.labelize(worker, job, queue)
               || worker === "ActiveJob::QueueAdapters::SidekiqAdapter::JobWrapper"
             labels[:worker] = job["wrapped"]
           else
-            labels[:worker] = worker.to_s
+            labels[:worker] = worker.class.to_s
           end
           labels
         end
diff --git a/prome.gemspec b/prome.gemspec
index ad19e67..b76bfb3 100644
--- a/prome.gemspec
+++ b/prome.gemspec
@@ -26,5 +26,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "minitest", "~> 5.0"
 
   spec.add_dependency "rails", "> 5.0.0"
-  spec.add_dependency "prometheus-client", "0.6.0"
+  spec.add_dependency "prometheus-client", "~> 0.6.0"
 end