diff --git a/lib/puppet/provider/mongodb_database/mongodb.rb b/lib/puppet/provider/mongodb_database/mongodb.rb
index 842252fcc..262cda789 100644
--- a/lib/puppet/provider/mongodb_database/mongodb.rb
+++ b/lib/puppet/provider/mongodb_database/mongodb.rb
@@ -23,7 +23,7 @@ def self.instances
       rs.slaveOk()
     }
     '
-    mongo_eval_result = mongo_eval(pre_cmd + ';JSON.stringify(db.getMongo().getDBs())')
+    mongo_eval_result = mongo_eval("#{pre_cmd};JSON.stringify(db.getMongo().getDBs())")
     pp mongo_eval_result
     dbs = JSON.parse mongo_eval_result