diff --git a/doc/proto_00000501.txt b/doc/proto_00000501.txt
index 4b36685..5b7fc5d 100644
--- a/doc/proto_00000501.txt
+++ b/doc/proto_00000501.txt
@@ -54,10 +54,12 @@ Client sends:
 	5 bits coded as Base32 char, meaning userid
 	5 bits coded as Base32 char, with value 5 or 6, representing number of raw
 	bits per encoded byte
+	CMC
 Server sends:
 	Name of codec if accepted. After this all upstream data packets must 
 	be encoded with the new codec.
 	BADCODEC if not accepted. Client must then revert to Base32
+	BADLEN if length of query is too short
 
 Probe downstream fragment size:
 Client sends:
diff --git a/src/iodine.c b/src/iodine.c
index 407de6e..c658021 100644
--- a/src/iodine.c
+++ b/src/iodine.c
@@ -476,9 +476,14 @@ send_version(int fd, uint32_t version)
 static void
 send_ip_request(int fd, int userid)
 {
-	char buf[512] = "I_.";
+	char buf[512] = "I____.";
 	buf[1] = b32_5to8(userid);
 	
+	buf[2] = b32_5to8((rand_seed >> 10) & 0x1f);
+	buf[3] = b32_5to8((rand_seed >> 5) & 0x1f);
+	buf[4] = b32_5to8((rand_seed ) & 0x1f);
+	rand_seed++;
+
 	strncat(buf, topdomain, 512 - strlen(buf));
 	send_query(fd, buf);
 }
@@ -498,10 +503,15 @@ send_case_check(int fd)
 static void
 send_codec_switch(int fd, int userid, int bits)
 {
-	char buf[512] = "S__.";
+	char buf[512] = "S_____.";
 	buf[1] = b32_5to8(userid);
 	buf[2] = b32_5to8(bits);
 	
+	buf[3] = b32_5to8((rand_seed >> 10) & 0x1f);
+	buf[4] = b32_5to8((rand_seed >> 5) & 0x1f);
+	buf[5] = b32_5to8((rand_seed ) & 0x1f);
+	rand_seed++;
+
 	strncat(buf, topdomain, 512 - strlen(buf));
 	send_query(fd, buf);
 }
diff --git a/src/iodined.c b/src/iodined.c
index 5a92c20..3f06c29 100644
--- a/src/iodined.c
+++ b/src/iodined.c
@@ -425,7 +425,7 @@ handle_null_request(int tun_fd, int dns_fd, struct query *q, int domain_len)
 	} else if(in[0] == 'S' || in[0] == 's') {
 		int codec;
 		struct encoder *enc;
-		if (domain_len != 4) { /* len = 4, example: "S15." */
+		if (domain_len < 3) { /* len at least 3, example: "S15" */
 			write_dns(dns_fd, q, "BADLEN", 6);
 			return;
 		}