diff --git a/domain-server/src/main.cpp b/domain-server/src/main.cpp
index 3bc40efc07..6988137455 100644
--- a/domain-server/src/main.cpp
+++ b/domain-server/src/main.cpp
@@ -127,14 +127,14 @@ int main(int argc, const char * argv[])
             currentBufferPos = broadcastPacket + sizeof(PACKET_HEADER);
             startPointer = currentBufferPos;
             
-            char* agentTypesOfInterest = (char*) currentBufferPos + sizeof(AGENT_TYPE) + numBytesSocket;
-            int numInterestTypes = strlen(agentTypesOfInterest);
+            char* agentTypesOfInterest = (char*) currentBufferPos + sizeof(AGENT_TYPE) + numBytesSocket + sizeof(unsigned char);
+            int numInterestTypes = *(agentTypesOfInterest - 1);
             
             if (numInterestTypes > 0) {
                 // if the agent has sent no types of interest, assume they want nothing but their own ID back
                 for (AgentList::iterator agent = agentList->begin(); agent != agentList->end(); agent++) {
                     if (!agent->matches((sockaddr*) &agentPublicAddress, (sockaddr*) &agentLocalAddress, agentType)
-                        && memchr(agentTypesOfInterest, agent->getType(), strlen(agentTypesOfInterest))) {
+                        && memchr(agentTypesOfInterest, agent->getType(), numInterestTypes)) {
                         // this is not the agent themselves
                         // and this is an agent of a type in the passed agent types of interest
                         // or the agent did not pass us any specific types they are interested in
diff --git a/libraries/shared/src/AgentList.cpp b/libraries/shared/src/AgentList.cpp
index 6f38bff519..1da6b90c2d 100644
--- a/libraries/shared/src/AgentList.cpp
+++ b/libraries/shared/src/AgentList.cpp
@@ -208,11 +208,11 @@ void AgentList::sendDomainServerCheckIn() {
     static unsigned char* checkInPacket = NULL;
 
     if (!checkInPacket) {
-        int numBytesAgentsOfInterest = _agentTypesOfInterest ? strlen((char*) _agentTypesOfInterest) : NULL;
+        int numBytesAgentsOfInterest = _agentTypesOfInterest ? strlen((char*) _agentTypesOfInterest) : 0;
         
         // check in packet has header, agent type, port, IP, agent types of interest, null termination
         int numPacketBytes = sizeof(PACKET_HEADER) + sizeof(AGENT_TYPE) + sizeof(uint16_t) + (sizeof(char) * 4) +
-            numBytesAgentsOfInterest + sizeof(char);
+            numBytesAgentsOfInterest + sizeof(unsigned char);
         
         checkInPacket = new unsigned char[numPacketBytes];
         
@@ -223,14 +223,15 @@ void AgentList::sendDomainServerCheckIn() {
         
         packSocket(checkInPacket + sizeof(PACKET_HEADER) + sizeof(AGENT_TYPE), getLocalAddress(), htons(_socketListenPort));
         
+        // add the number of bytes for agent types of interest
+        checkInPacket[numPacketBytes] = numBytesAgentsOfInterest;
+                
         // copy over the bytes for agent types of interest, if required
         if (numBytesAgentsOfInterest > 0) {
-            memcpy(checkInPacket + numPacketBytes - sizeof(char) - numBytesAgentsOfInterest,
+            memcpy(checkInPacket + numPacketBytes + sizeof(unsigned char),
                    _agentTypesOfInterest,
                    numBytesAgentsOfInterest);
         }
-        
-        checkInPacket[numPacketBytes - 1] = '\0';
     }
     
     _agentSocket.send(DOMAIN_IP, DOMAINSERVER_PORT, checkInPacket, strlen((char*) checkInPacket));