diff --git a/apps/openmw/mwworld/class.cpp b/apps/openmw/mwworld/class.cpp
index 876328641a..1eb2f35bd0 100644
--- a/apps/openmw/mwworld/class.cpp
+++ b/apps/openmw/mwworld/class.cpp
@@ -184,10 +184,13 @@ namespace MWWorld
 
     const Class& Class::get (const std::string& key)
     {
+        if (key.empty())
+            throw std::logic_error ("Class::get(): attempting to get an empty key");
+
         std::map<std::string, boost::shared_ptr<Class> >::const_iterator iter = sClasses.find (key);
 
         if (iter==sClasses.end())
-            throw std::logic_error ("unknown class key: " + key);
+            throw std::logic_error ("Class::get(): unknown class key: " + key);
 
         return *iter->second;
     }