diff --git a/src/utils/introspectionRegistry.cpp b/src/utils/introspectionRegistry.cpp
index 0d25665..b5aef77 100644
--- a/src/utils/introspectionRegistry.cpp
+++ b/src/utils/introspectionRegistry.cpp
@@ -36,21 +36,6 @@ void IntrospectionRegistry::reset()
     _registry.clear();
 }
 
-FieldConstPtr IntrospectionRegistry::getIntrospectionInterface(const int16 id)
-{
-    registryMap_t::iterator registryIter = _registry.find(id);
-    if(registryIter == _registry.end())
-    {
-        return FieldConstPtr();
-    }
-    return registryIter->second;
-}
-
-void IntrospectionRegistry::registerIntrospectionInterface(const int16 id, FieldConstPtr const & field)
-{
-    _registry[id] = field;
-}
-
 int16 IntrospectionRegistry::registerIntrospectionInterface(FieldConstPtr const & field, bool& existing)
 {
     int16 key;
@@ -127,8 +112,17 @@ FieldConstPtr IntrospectionRegistry::deserialize(ByteBuffer* buffer, Deserializa
     }
     else if (typeCode == ONLY_ID_TYPE_CODE)
     {
-        control->ensureData(sizeof(int16)/sizeof(int8));
-        return getIntrospectionInterface(buffer->getShort());
+        control->ensureData(sizeof(int16));
+        int16 id = buffer->getShort();
+
+        registryMap_t::iterator registryIter = _registry.find(id);
+        if(registryIter == _registry.end())
+        {
+            // peer gave us an id which we don't remember.
+            // This isn't recoverable.
+            throw std::runtime_error("IntrospectionRegistry miss.");
+        }
+        return registryIter->second;
     }
     // could also be a mask
     if(typeCode == IntrospectionRegistry::FULL_WITH_ID_TYPE_CODE)
@@ -136,7 +130,7 @@ FieldConstPtr IntrospectionRegistry::deserialize(ByteBuffer* buffer, Deserializa
         control->ensureData(sizeof(int16)/sizeof(int8));
         const short key = buffer->getShort();
         FieldConstPtr field = _fieldCreate->deserialize(buffer, control);
-        registerIntrospectionInterface(key, field);
+        _registry[key] = field;
         return field;
     }
 
diff --git a/src/utils/pv/introspectionRegistry.h b/src/utils/pv/introspectionRegistry.h
index 36b176e..c37bdaa 100644
--- a/src/utils/pv/introspectionRegistry.h
+++ b/src/utils/pv/introspectionRegistry.h
@@ -51,23 +51,8 @@ public:
      * Resets registry, i.e. must be done when transport is changed (server restarted).
      */
     void reset();
-    /**
-     * Get introspection interface for given ID.
-     *
-     * @param id id of the introspection interface to get
-     *
-     * @return <code>Field</code> instance for given ID.
-     */
-    epics::pvData::FieldConstPtr getIntrospectionInterface(const epics::pvData::int16 id);
-
-    /**
-     * Registers introspection interface with given ID. Always INCOMING.
-     *
-     * @param id id of the introspection interface to register
-     * @param field introspection interface to register
-     */
-    void registerIntrospectionInterface(const epics::pvData::int16 id, epics::pvData::FieldConstPtr const & field);
 
+private:
     /**
      * Registers introspection interface and get it's ID. Always OUTGOING.
      * If it is already registered only preassigned ID is returned.
@@ -79,7 +64,7 @@ public:
      * @return id of given introspection interface
      */
     epics::pvData::int16 registerIntrospectionInterface(epics::pvData::FieldConstPtr const & field, bool& existing);
-
+public:
     /**
      * Serializes introspection interface
      *