diff --git a/lib/sidekiq/processor.rb b/lib/sidekiq/processor.rb
index 315c1bc5..4d31dceb 100644
--- a/lib/sidekiq/processor.rb
+++ b/lib/sidekiq/processor.rb
@@ -217,7 +217,9 @@ module Sidekiq
       names.shift if names.empty? || names.first.empty?
 
       names.inject(Object) do |constant, name|
-        constant.const_defined?(name) ? constant.const_get(name) : constant.const_missing(name)
+        # the false flag limits search for name to under the constant namespace
+        #   which mimics Rails' behaviour
+        constant.const_defined?(name, false) ? constant.const_get(name, false) : constant.const_missing(name)
       end
     end