diff --git a/src/peer_connection.cpp b/src/peer_connection.cpp
index a0e9639a1..7c3a58537 100755
--- a/src/peer_connection.cpp
+++ b/src/peer_connection.cpp
@@ -957,6 +957,7 @@ namespace libtorrent
 	{
 		assert(!m_socket->is_blocking());
 		assert(m_packet_size > 0);
+		assert(m_socket->is_readable());
 		for(;;)
 		{
 			assert(m_packet_size > 0);
@@ -1422,4 +1423,4 @@ namespace libtorrent
 			send_buffer_updated();
 		}
 	}
-}
\ No newline at end of file
+}