diff --git a/src/ripple/protocol/impl/ErrorCodes.cpp b/src/ripple/protocol/impl/ErrorCodes.cpp
index c6a97a515..aebab6f0e 100644
--- a/src/ripple/protocol/impl/ErrorCodes.cpp
+++ b/src/ripple/protocol/impl/ErrorCodes.cpp
@@ -122,6 +122,7 @@ public:
     ErrorInfo const& get (error_code_i code) const
     {
         Map::const_iterator const iter (m_map.find (code));
+        assert (iter != m_map.end());
         if (iter != m_map.end())
             return iter->second;
         return m_unknown;