diff --git a/MdeModulePkg/Universal/Network/Tcp4Dxe/Tcp4Output.c b/MdeModulePkg/Universal/Network/Tcp4Dxe/Tcp4Output.c
index b984ac069e..0eec8f07b9 100644
--- a/MdeModulePkg/Universal/Network/Tcp4Dxe/Tcp4Output.c
+++ b/MdeModulePkg/Universal/Network/Tcp4Dxe/Tcp4Output.c
@@ -754,7 +754,7 @@ SEND_AGAIN:
   Len   = TcpDataToSend (Tcb, Force);
   Seq   = Tcb->SndNxt;
 
-  ASSERT ((Tcb->State) < (sizeof (mTcpOutFlag) / sizeof (mTcpOutFlag[0])));
+  ASSERT ((Tcb->State) < (ARRAY_SIZE (mTcpOutFlag)));
   Flag  = mTcpOutFlag[Tcb->State];
 
   if ((Flag & TCP_FLG_SYN) != 0) {