diff --git a/lib/ddtrace/contrib/rails/framework.rb b/lib/ddtrace/contrib/rails/framework.rb
index c8af12e6fef..6bb8084733a 100644
--- a/lib/ddtrace/contrib/rails/framework.rb
+++ b/lib/ddtrace/contrib/rails/framework.rb
@@ -12,7 +12,7 @@
 require 'ddtrace/contrib/rails/utils'
 
 # Rails < 3.1
-unless defined?(ActiveRecord::Base.connection_config)
+if defined?(::ActiveRecord) && !defined?(::ActiveRecord::Base.connection_config)
   ActiveRecord::Base.class_eval do
     class << self
       def connection_config