diff --git a/commandline.c b/commandline.c
index 4a9271af..f9842cdd 100644
--- a/commandline.c
+++ b/commandline.c
@@ -428,6 +428,11 @@ int app_echo(int argc, const char *const *argv, struct command_line_option *o)
   return 0;
 }
 
+int cli_lookup_did(const char *text)
+{
+  return text[0] == '\0' || strcmp(text, "*") || str_is_did(text);
+}
+
 int app_dna_lookup(int argc, const char *const *argv, struct command_line_option *o)
 {
   int i;
@@ -441,7 +446,7 @@ int app_dna_lookup(int argc, const char *const *argv, struct command_line_option
   char uris[MAXREPLIES][MAXURILEN];
 
   const char *did;
-  if (cli_arg(argc, argv, o, "did", &did, NULL, "*") == -1)
+  if (cli_arg(argc, argv, o, "did", &did, cli_lookup_did, "*") == -1)
     return -1;
 
   /* Bind to MDP socket and await confirmation */
@@ -1407,15 +1412,19 @@ int app_keyring_add(int argc, const char *const *argv, struct command_line_optio
   return 0;
 }
 
+int cli_optional_did(const char *text)
+{
+  return text[0] == '\0' || str_is_did(text);
+}
+
 int app_keyring_set_did(int argc, const char *const *argv, struct command_line_option *o)
 {
   const char *sid, *did, *pin, *name;
-  cli_arg(argc, argv, o, "sid", &sid, NULL, "");
-  cli_arg(argc, argv, o, "did", &did, NULL, "");
+  cli_arg(argc, argv, o, "sid", &sid, str_is_subscriber_id, "");
+  cli_arg(argc, argv, o, "did", &did, str_is_did, "");
   cli_arg(argc, argv, o, "name", &name, NULL, "");
   cli_arg(argc, argv, o, "pin", &pin, NULL, "");
 
-  if (strlen(did)>31) return WHY("DID too long (31 digits max)");
   if (strlen(name)>63) return WHY("Name too long (31 char max)");
 
   if (!(keyring = keyring_open_with_pins(pin)))
diff --git a/dataformats.c b/dataformats.c
index 527bebfe..aa5e84c2 100644
--- a/dataformats.c
+++ b/dataformats.c
@@ -99,7 +99,8 @@ int fromhexstr(unsigned char *dstBinary, const char *srcHex, size_t nbinary)
 
 int str_is_subscriber_id(const char *sid)
 {
-  return strcasecmp(sid, "broadcast") == 0 || _is_xstring(sid, SID_STRLEN);
+  size_t len = 0;
+  return strn_is_subscriber_id(sid, &len) && sid[len] == '\0';
 }
 
 int strn_is_subscriber_id(const char *sid, size_t *lenp)
@@ -157,6 +158,32 @@ int rhizome_str_is_file_hash(const char *hash)
   return _is_xstring(hash, RHIZOME_FILEHASH_STRLEN);
 }
 
+int str_is_did(const char *did)
+{
+  size_t len = 0;
+  return strn_is_did(did, &len) && did[len] == '\0';
+}
+
+int strn_is_did(const char *did, size_t *lenp)
+{
+  int i;
+  for (i = 0; i < DID_MAXSIZE; ++i) {
+    switch (did[i]) {
+      case '0': case '1': case '2': case '3': case '4':
+      case '5': case '6': case '7': case '8': case '9':
+      case '*': case '#': case '+':
+	break;
+      default:
+	return 0;
+    }
+  }
+  if (i < DID_MINSIZE)
+    return 0;
+  if (lenp)
+    *lenp = i;
+  return 1;
+}
+
 int extractDid(unsigned char *packet,int *ofs,char *did)
 {
   int d=0;
diff --git a/serval.h b/serval.h
index 35dd4f1f..da1ce86e 100755
--- a/serval.h
+++ b/serval.h
@@ -300,6 +300,7 @@ void keyring_identity_extract(const keyring_identity *id, const unsigned char **
 
 */
 #define SID_SIZE 32 
+#define DID_MINSIZE 5
 #define DID_MAXSIZE 32
 #define SIDDIDFIELD_LEN (SID_SIZE+1)
 #define PINFIELD_LEN 32
@@ -688,6 +689,8 @@ char *str_toupper_inplace(char *s);
 
 int str_is_subscriber_id(const char *sid);
 int strn_is_subscriber_id(const char *sid, size_t *lenp);
+int str_is_did(const char *did);
+int strn_is_did(const char *did, size_t *lenp);
 
 int stowSid(unsigned char *packet, int ofs, const char *sid);
 int stowDid(unsigned char *packet,int *ofs,char *did);
diff --git a/tests/dnahelper b/tests/dnahelper
index 7b1f9b2b..6f3749cf 100755
--- a/tests/dnahelper
+++ b/tests/dnahelper
@@ -43,64 +43,78 @@ configure_servald_server() {
 
 setup_dnahelper() {
    dnahelper="$TFWTMP/dnahelper"
-   cat >"$dnahelper" <<EOF
-#!/usr/bin/env python
-# Sample DNA Helper application for testing
-import sys
-def main():
-   print "STARTED"
-   sys.stdout.flush()
-   while True:
-      #sys.stderr.write("wah\n")
-      line = sys.stdin.readline().strip()
-      if line == "":
-         # EOF detection is broken :(
-         break
-      s = line.split('|')
-      if len(s) != 3:
-         print "ERROR"
-         continue
-      (token, number, xxx) = s
-      if number == "12345":
-         # Multiple results (SID/VoMP results)
-         print "%s|sid:%s|%s|%s|" % (token, token, number, "Agent A. Smith")
-         print "%s|sid:%s|%s|%s|" % (token, token, number, "Agent B. Smith")
-      elif number == "5551234":
-         # Single result, SIP URI
-         print "%s|sip://5551234@10.1.2.3|%s|%s|" % (token, number, "Will Smith")
-      elif number == "5551001":
-         # Empty URI field
-         print "%s||%s|%s|" % (token, number, "Empty URI")
-      elif number == "5551002":
-         # Empty DID field
-         print "%s|sip://123@1.2.3.4||%s|" % (token, "Empty DID")
-      elif number == "5551003":
-         # Empty CALLERID field
-         print "%s|sip://empty-callerid@1.2.3.4|%s||" % (token, number)
-      elif number == "5551004":
-         # Excessively long callerid
-         print "%s|sip://long-callerid@1.2.3.4|%s|%s|" % (token, 'x' * 200, number)
-      elif number == "5551005":
-         # Excessively long DID
-         print "%s|sip://long-did@1.2.3.4|%s|%s|" % (token, 'x' * 200, "Agent Smith")
-      elif number == "5551006":
-         # Excessively long URI
-         print "%s|sip://%s|%s|%s|" % (token, 'x' * 1000, number, "Agent Smith")
-      elif number == "5551007":
-         # Incorrect token
-         print "cheeseburger|sip://incorrect-token@1.2.3.4|%s||" % (token, number)
-      elif number == "11111":
-         print "%s|A|%s|B|" % (token, number)
-      print "DONE"
-      sys.stdout.flush()
-if __name__ == "__main__":
-   main()
+   cat >"$dnahelper" <<'EOF'
+#!/bin/sh
+echo STARTED
+while read line
+do
+   token="${line%%|*}"
+   line="${line#*|}"
+   did="${line%%|*}"
+   line="${line#*|}"
+   case "$token|$did|$line" in
+   '|'*'|')
+      echo "empty token" >&2
+      ;;
+   *'||')
+      echo "empty DID" >&2
+      ;;
+   *'|00000|')
+      echo "$token|A|$did|B|"
+      ;;
+   *'|00001|')
+      echo "$token|sip://$token@10.1.0.1|$did|Joe A. Bloggs|"
+      ;;
+   *'|00002|')
+      echo "$token|sip://$token@10.1.0.1|$did|Joe A. Bloggs|"
+      sleep 0.1
+      echo "$token|sip://$token@10.1.0.2|$did|Joe B. Bloggs|"
+      sleep 0.1
+      ;;
+   *'|00003|')
+      echo "$token|sip://$token@10.1.0.1|$did|Joe A. Bloggs|"
+      sleep 0.1
+      echo "$token|sip://$token@10.1.0.2|$did|Joe B. Bloggs|"
+      sleep 0.1
+      echo "$token|sip://$token@10.1.0.3|$did|Joe C. Bloggs|"
+      sleep 0.1
+      ;;
+   *'|00004|')
+      # Empty URI
+      echo "$token||$did|Eccles|"
+      ;;
+   # Test malformed URI
+   # Test mismatched token
+   # Test empty token
+   # Test long token
+   # Test empty DID
+   # Test mismatched DID
+   # Test long DID
+   # Test malformed line
+   # Test long reply
+   # Test DONE timeout
+   # Test die
+   # Test fork and die
+   *'|'*'|')
+      ;;
+   *)
+      echo "garbage line" >&2
+      ;;
+   esac
+   echo DONE
+done
 EOF
    chmod 0755 "$dnahelper"
    executeOk "$dnahelper" <<EOF
-ToKeN|11111|
+ToKeN|00000|
 EOF
-   assertStdoutIs -e "STARTED\nToKeN|A|11111|B|\nDONE\n"
+   assertStdoutIs -e "STARTED\nToKeN|A|00000|B|\nDONE\n"
+}
+
+setup_single_instance() {
+   setup
+   setup_dnahelper
+   start_servald_instances +A
 }
 
 doc_ExecError="Non-existent DNA helper executable"
@@ -114,15 +128,40 @@ test_ExecError() {
    executeOk_servald dna lookup 12345
 }
 
-doc_Simple="Simple DNA helper test"
-setup_Simple() {
-   setup
-   setup_dnahelper
-   start_servald_instances +A
+doc_OneReply="DNA helper returns one line"
+setup_OneReply() {
+   setup_single_instance
 }
-test_Simple() {
-   executeOk_servald dna lookup 12345
-   tfw_cat --stdout --stderr
+test_OneReply() {
+   executeOk_servald dna lookup 00001
+   assertStdoutIs -e "sip://$SIDA@10.1.0.1:00001:Joe A. Bloggs\n"
+}
+
+doc_TwoReplies="DNA helper returns two lines"
+setup_TwoReplies() {
+   setup_single_instance
+}
+test_TwoReplies() {
+   executeOk_servald dna lookup 00002
+   assertStdoutIs -e "sip://$SIDA@10.1.0.1:00002:Joe A. Bloggs\nsip://$SIDA@10.1.0.2:00002:Joe B. Bloggs\n"
+}
+
+doc_ThreeReplies="DNA helper returns three lines"
+setup_ThreeReplies() {
+   setup_single_instance
+}
+test_ThreeReplies() {
+   executeOk_servald dna lookup 00003
+   assertStdoutIs -e "sip://$SIDA@10.1.0.1:00003:Joe A. Bloggs\nsip://$SIDA@10.1.0.2:00003:Joe B. Bloggs\nsip://$SIDA@10.1.0.3:00003:Joe C. Bloggs\n"
+}
+
+doc_EmptyURI="DNA helper returns empry URI"
+setup_EmptyURI() {
+   setup_single_instance
+}
+test_EmptyURI() {
+   executeOk_servald dna lookup 00004
+   assertStdoutIs ""
 }
 
 runTests "$@"