diff --git a/fec_manager.cpp b/fec_manager.cpp
index 46747f6..c37b85c 100644
--- a/fec_manager.cpp
+++ b/fec_manager.cpp
@@ -220,11 +220,22 @@ int fec_encode_manager_t::input(char *s,int len/*,int &is_first_packet*/)
 
 	if(fec_mode==0&& s!=0 &&counter==0)
 	{
-		int out_len=blob_encode.get_shard_len(fec_data_num,len);
-		if(out_len>fec_mtu)
+		if(fec_data_num==1)
 		{
-			mylog(log_warn,"message too long ori_len=%d out_len=%d fec_mtu=%d,ignored\n",len,out_len,fec_mtu);
-			return -1;
+			if(len>fec_mtu)
+			{
+				mylog(log_warn,"message too long for fec_data_num=1, len=%d fec_mtu=%d,ignored\n",len,fec_mtu);
+				return -1;
+			}
+		}
+		else
+		{
+			int out_len=blob_encode.get_shard_len(fec_data_num,len);
+			if(out_len>fec_mtu)
+			{
+				mylog(log_warn,"message too long ori_len=%d out_len=%d fec_mtu=%d,ignored\n",len,out_len,fec_mtu);
+				return -1;
+			}
 		}
 	}
 	if(fec_mode==1&&s!=0&&len>fec_mtu)