diff --git a/libi2pd/SSU2Session.cpp b/libi2pd/SSU2Session.cpp
index 1fe00982..e10d5a20 100644
--- a/libi2pd/SSU2Session.cpp
+++ b/libi2pd/SSU2Session.cpp
@@ -292,8 +292,11 @@ namespace transport
 #if OPENSSL_PQ
 			m_PQKeys.reset (nullptr);
 #endif
-			if (!m_IntermediateQueue.empty ())
-				m_SendQueue.splice (m_SendQueue.end (), m_IntermediateQueue);
+			{
+				std::lock_guard<std::mutex> l(m_IntermediateQueueMutex);
+				if (!m_IntermediateQueue.empty ())
+					m_SendQueue.splice (m_SendQueue.end (), m_IntermediateQueue);
+			}
 			for (auto& it: m_SendQueue)
 				it->Drop ();
 			m_SendQueue.clear ();