diff --git a/include/libtorrent/kademlia/observer.hpp b/include/libtorrent/kademlia/observer.hpp
index 254129968..b8fb1a171 100644
--- a/include/libtorrent/kademlia/observer.hpp
+++ b/include/libtorrent/kademlia/observer.hpp
@@ -82,10 +82,12 @@ struct observer : boost::noncopyable
 		m_in_constructor = true;
 		m_was_sent = false;
 		m_was_abandoned = false;
+		m_in_use = true;
 #endif
 		set_target(ep);
 	}
 
+	// defined in rpc_manager.cpp
 	virtual ~observer();
 
 	// this is called when a reply is received
@@ -167,6 +169,7 @@ public:
 	bool m_in_constructor:1;
 	bool m_was_sent:1;
 	bool m_was_abandoned:1;
+	bool m_in_use:1;
 #endif
 };
 
diff --git a/src/kademlia/rpc_manager.cpp b/src/kademlia/rpc_manager.cpp
index b61b23936..7be84086a 100644
--- a/src/kademlia/rpc_manager.cpp
+++ b/src/kademlia/rpc_manager.cpp
@@ -216,7 +216,11 @@ void* rpc_manager::allocate_observer()
 {
 	m_pool_allocator.set_next_size(10);
 	void* ret = m_pool_allocator.malloc();
-	if (ret) ++m_allocated_observers;
+	if (ret)
+	{
+		++m_allocated_observers;
+		TORRENT_ASSERT(reinterpret_cast<observer*>(ret)->m_in_use == false);
+	}
 	return ret;
 }
 
@@ -224,6 +228,7 @@ void rpc_manager::free_observer(void* ptr)
 {
 	if (!ptr) return;
 	--m_allocated_observers;
+	TORRENT_ASSERT(reinterpret_cast<observer*>(ptr)->m_in_use == true);
 	m_pool_allocator.free(ptr);
 }
 
@@ -502,6 +507,10 @@ observer::~observer()
 	// reported back
 	TORRENT_ASSERT(m_was_sent == bool(flags & flag_done) || m_was_abandoned);
 	TORRENT_ASSERT(!m_in_constructor);
+#if defined TORRENT_DEBUG || TORRENT_RELEASE_ASSERTS
+	TORRENT_ASSERT(m_in_use);
+	m_in_use = false;
+#endif
 }
 
 } } // namespace libtorrent::dht