diff --git a/src/net_helper.c b/src/net_helper.c
index e71abd9b0..84e6b86d8 100644
--- a/src/net_helper.c
+++ b/src/net_helper.c
@@ -605,8 +605,8 @@ static int sample_conv_tcp_options_list(const struct arg *arg_p, struct sample *
 		/* kind1 = NOP and is a single byte, others have a length field */
 		if (smp->data.u.str.area[ofs] == 1)
 			ofs++;
-		else if (ofs + 1 < len)
-			ofs += smp->data.u.str.area[ofs + 1];
+		else if (ofs + 1 < len && smp->data.u.str.area[ofs + 1])
+			ofs += (uchar)smp->data.u.str.area[ofs + 1];
 		else
 			break;
 	}