diff --git a/packetWin7/npf/npf/Loopback.c b/packetWin7/npf/npf/Loopback.c
index b16fe9f8..76df81d2 100644
--- a/packetWin7/npf/npf/Loopback.c
+++ b/packetWin7/npf/npf/Loopback.c
@@ -542,7 +542,7 @@ NPF_NetworkClassifyInbound(
 
 	TRACE_ENTER();
 
-	if (!NPF_ShouldProcess(inFixedValues, inMetaValues, &bIPv4))
+	if (pNetBufferList == NULL || !NPF_ShouldProcess(inFixedValues, inMetaValues, &bIPv4))
 	{
 		return;
 	}