diff --git a/extensions/sdktools/extension.cpp b/extensions/sdktools/extension.cpp
index d799b18c..6481baf6 100644
--- a/extensions/sdktools/extension.cpp
+++ b/extensions/sdktools/extension.cpp
@@ -97,3 +97,26 @@ bool SDKTools::QueryRunning(char *error, size_t maxlength)
 
 	return true;
 }
+
+bool SDKTools::QueryInterfaceDrop(SMInterface *pInterface)
+{
+	if (pInterface == g_pBinTools)
+	{
+		return false;
+	}
+
+	return IExtensionInterface::QueryInterfaceDrop(pInterface);
+}
+
+void SDKTools::NotifyInterfaceDrop(SMInterface *pInterface)
+{
+	List<ValveCall *>::iterator iter;
+	for (iter = g_RegCalls.begin();
+		iter != g_RegCalls.end();
+		iter++)
+	{
+		delete (*iter);
+	}
+	g_RegCalls.clear();
+
+}
diff --git a/extensions/sdktools/extension.h b/extensions/sdktools/extension.h
index 48cde279..9693a67c 100644
--- a/extensions/sdktools/extension.h
+++ b/extensions/sdktools/extension.h
@@ -47,6 +47,8 @@ public:
 	virtual void SDK_OnAllLoaded();
 	//virtual void SDK_OnPauseChange(bool paused);
 	virtual bool QueryRunning(char *error, size_t maxlength);
+	virtual bool QueryInterfaceDrop(SMInterface *pInterface);
+	virtual void NotifyInterfaceDrop(SMInterface *pInterface);
 public:
 #if defined SMEXT_CONF_METAMOD
 	virtual bool SDK_OnMetamodLoad(ISmmAPI *ismm, char *error, size_t maxlen, bool late);