diff --git a/eth_interface.c b/eth_interface.c
index 101fe93..b6883d9 100644
--- a/eth_interface.c
+++ b/eth_interface.c
@@ -35,7 +35,7 @@ EthInterface *ethintf_new(EthIODef * io) {
 
     ethIntf->txQ = mq_create(ETHLIB_DEF_MQ_SIZE);
     ethIntf->rxQ = mq_create(ETHLIB_DEF_MQ_SIZE);
-    ETHLIB_OS_SEM_CREATE(&ethIntf->rxSem);
+    ETHLIB_OS_SEM_CREATE(&ethIntf->rxSem, ETHLIB_DEF_MQ_SIZE);
     ETHLIB_OS_THREAD_DEFINE(ethinf_proc_thread, ipp, osPriorityHigh, 4096, ethIntf);
     ETHLIB_OS_THREAD_CREATE(ipp, ethIntf);