diff --git a/core/federated/RTI/rti_remote.c b/core/federated/RTI/rti_remote.c
index c5bd02955..2ca3ad139 100644
--- a/core/federated/RTI/rti_remote.c
+++ b/core/federated/RTI/rti_remote.c
@@ -797,7 +797,7 @@ void* clock_synchronization_thread(void* noargs) {
       send_physical_clock(MSG_TYPE_CLOCK_SYNC_T1, fed, UDP);
 
       // Listen for reply message, which should be T3.
-      size_t message_size = 1 + sizeof(int32_t);
+      size_t message_size = 1 + sizeof(uint16_t);
       unsigned char buffer[message_size];
       // Maximum number of messages that we discard before giving up on this cycle.
       // If the T3 message from this federate does not arrive and we keep receiving
@@ -809,7 +809,7 @@ void* clock_synchronization_thread(void* noargs) {
         // If any errors occur, either discard the message or the clock sync round.
         if (!read_failed) {
           if (buffer[0] == MSG_TYPE_CLOCK_SYNC_T3) {
-            int32_t fed_id_2 = extract_int32(&(buffer[1]));
+            uint16_t fed_id_2 = extract_uint16(&(buffer[1]));
             // Check that this message came from the correct federate.
             if (fed_id_2 != fed->enclave.id) {
               // Message is from the wrong federate. Discard the message.
@@ -1298,14 +1298,12 @@ static int receive_udp_message_and_set_up_clock_sync(int* socket_id, uint16_t fe
           send_physical_clock(MSG_TYPE_CLOCK_SYNC_T1, fed, TCP);
 
           // Listen for reply message, which should be T3.
-          size_t message_size = 1 + sizeof(int32_t);
+          size_t message_size = 1 + sizeof(uint16_t);
           unsigned char buffer[message_size];
           read_from_socket_fail_on_error(socket_id, message_size, buffer, NULL,
                                          "Socket to federate %d unexpectedly closed.", fed_id);
           if (buffer[0] == MSG_TYPE_CLOCK_SYNC_T3) {
-            int32_t fed_id = extract_int32(&(buffer[1]));
-            assert(fed_id > -1);
-            assert(fed_id < 65536);
+            uint16_t fed_id = extract_uint16(&(buffer[1]));
             LF_PRINT_DEBUG("RTI received T3 clock sync message from federate %d.", fed_id);
             handle_physical_clock_sync_message(fed, TCP);
           } else {
diff --git a/core/federated/clock-sync.c b/core/federated/clock-sync.c
index 741182735..60a7bd16f 100644
--- a/core/federated/clock-sync.c
+++ b/core/federated/clock-sync.c
@@ -276,13 +276,13 @@ int handle_T1_clock_sync_message(unsigned char* buffer, int socket, instant_t t2
   // T3-T2 between receiving the T1 message and replying.
 
   // Reply will have the federate ID as a payload.
-  unsigned char reply_buffer[1 + sizeof(int)];
+  unsigned char reply_buffer[1 + sizeof(uint16_t)];
   reply_buffer[0] = MSG_TYPE_CLOCK_SYNC_T3;
-  encode_int32(_lf_my_fed_id, &(reply_buffer[1]));
+  encode_uint16(_lf_my_fed_id, &(reply_buffer[1]));
 
   // Write the reply to the socket.
   LF_PRINT_DEBUG("Sending T3 message to RTI.");
-  if (write_to_socket(socket, 1 + sizeof(int), reply_buffer)) {
+  if (write_to_socket(socket, 1 + sizeof(uint16_t), reply_buffer)) {
     lf_print_error("Clock sync: Failed to send T3 message to RTI.");
     return -1;
   }
diff --git a/core/federated/federate.c b/core/federated/federate.c
index 4b12f8b53..e9ed43710 100644
--- a/core/federated/federate.c
+++ b/core/federated/federate.c
@@ -1778,23 +1778,26 @@ void lf_connect_to_federate(uint16_t remote_federate_id) {
       return;
     }
 
-    // Check whether the RTI is still there.
-    if (rti_failed()) {
-      break;
-    }
-    // Connect was successful.
-    size_t buffer_length = 1 + sizeof(uint16_t) + 1;
-    unsigned char buffer[buffer_length];
-    buffer[0] = MSG_TYPE_P2P_SENDING_FED_ID;
-    if (_lf_my_fed_id > UINT16_MAX) {
-      // This error is very unlikely to occur.
-      lf_print_error_and_exit("Too many federates! More than %d.", UINT16_MAX);
-    }
-    encode_uint16((uint16_t)_lf_my_fed_id, (unsigned char*)&(buffer[1]));
-    unsigned char federation_id_length = (unsigned char)strnlen(federation_metadata.federation_id, 255);
-    buffer[sizeof(uint16_t) + 1] = federation_id_length;
-    // Trace the event when tracing is enabled
-    tracepoint_federate_to_federate(send_FED_ID, _lf_my_fed_id, remote_federate_id, NULL);
+      // Check whether the RTI is still there.
+      if (rti_failed())
+        break;
+
+      // Wait ADDRESS_QUERY_RETRY_INTERVAL nanoseconds.
+      lf_sleep(ADDRESS_QUERY_RETRY_INTERVAL);
+    } else {
+      // Connect was successful.
+      size_t buffer_length = 1 + sizeof(uint16_t) + 1;
+      unsigned char buffer[buffer_length];
+      buffer[0] = MSG_TYPE_P2P_SENDING_FED_ID;
+      if (_lf_my_fed_id == UINT16_MAX) {
+        // This error is very unlikely to occur.
+        lf_print_error_and_exit("Too many federates! More than %d.", UINT16_MAX -1);
+      }
+      encode_uint16((uint16_t)_lf_my_fed_id, (unsigned char*)&(buffer[1]));
+      unsigned char federation_id_length = (unsigned char)strnlen(federation_metadata.federation_id, 255);
+      buffer[sizeof(uint16_t) + 1] = federation_id_length;
+      // Trace the event when tracing is enabled
+      tracepoint_federate_to_federate(send_FED_ID, _lf_my_fed_id, remote_federate_id, NULL);
 
     // No need for a mutex because we have the only handle on the socket.
     write_to_socket_fail_on_error(&socket_id, buffer_length, buffer, NULL, "Failed to send fed_id to federate %d.",
@@ -1867,8 +1870,8 @@ void lf_connect_to_rti(const char* hostname, int port) {
     unsigned char buffer[4];
     buffer[0] = MSG_TYPE_FED_IDS;
     // Next send the federate ID.
-    if (_lf_my_fed_id > UINT16_MAX) {
-      lf_print_error_and_exit("Too many federates! More than %d.", UINT16_MAX);
+    if (_lf_my_fed_id == UINT16_MAX) {
+      lf_print_error_and_exit("Too many federates! More than %d.", UINT16_MAX - 1);
     }
     encode_uint16((uint16_t)_lf_my_fed_id, &buffer[1]);
     // Next send the federation ID length.
diff --git a/core/utils/util.c b/core/utils/util.c
index 4fb956b3a..f7c260af8 100644
--- a/core/utils/util.c
+++ b/core/utils/util.c
@@ -58,7 +58,7 @@ THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  * The ID of this federate. For a non-federated execution, this will be -1.
  * For a federated execution, it will be assigned in the generated code.
  */
-int _lf_my_fed_id = -1;
+uint16_t _lf_my_fed_id = UINT16_MAX; // Federate IDs are counted up from 0. If we hit this, we have too many.
 
 /**
  * If non-null, this function will be used instead of the printf to
@@ -69,7 +69,7 @@ print_message_function_t* print_message_function = NULL;
 /** The level of messages to redirect to print_message_function. */
 int print_message_level = -1;
 
-int lf_fed_id() { return _lf_my_fed_id; }
+uint16_t lf_fed_id() { return _lf_my_fed_id; }
 
 // Declaration needed to attach attributes to suppress warnings of the form:
 // "warning: function '_lf_message_print' might be a candidate for 'gnu_printf'
@@ -112,7 +112,7 @@ void _lf_message_print(const char* prefix, const char* format, va_list args,
     // interleaved between threads.
     // vprintf() is a version that takes an arg list rather than multiple args.
     char* message;
-    if (_lf_my_fed_id < 0) {
+    if (_lf_my_fed_id == UINT16_MAX) {
       size_t length = strlen(prefix) + strlen(format) + 32;
       message = (char*)malloc(length + 1);
       snprintf(message, length, "%s%s\n", prefix, format);
diff --git a/include/core/utils/util.h b/include/core/utils/util.h
index 2d9998a72..77b7b767d 100644
--- a/include/core/utils/util.h
+++ b/include/core/utils/util.h
@@ -86,12 +86,12 @@ typedef struct lf_stat_ll {
  * _lf_initialize_trigger_objects() is called.
  * @see xtext/org.icyphy.linguafranca/src/org/icyphy/generator/CGenerator.xtend.
  */
-extern int _lf_my_fed_id;
+extern uint16_t _lf_my_fed_id;
 
 /**
  * Return the federate ID or -1 if this program is not part of a federation.
  */
-int lf_fed_id(void);
+uint16_t lf_fed_id(void);
 
 /**
  * varargs alternative of "lf_print"