diff --git a/libi2pd/TunnelBase.h b/libi2pd/TunnelBase.h
index 8b7fb408..97fb2b51 100644
--- a/libi2pd/TunnelBase.h
+++ b/libi2pd/TunnelBase.h
@@ -59,7 +59,7 @@ namespace tunnel
 
 	struct TunnelCreationTimeCmp
 	{
-		bool operator() (std::shared_ptr<const TunnelBase> t1, std::shared_ptr<const TunnelBase> t2) const
+		bool operator() (const std::shared_ptr<const TunnelBase> & t1, const std::shared_ptr<const TunnelBase> & t2) const
 		{
 			if (t1->GetCreationTime () != t2->GetCreationTime ())
 				return t1->GetCreationTime () > t2->GetCreationTime ();