diff --git a/examples/companion_radio/MyMesh.cpp b/examples/companion_radio/MyMesh.cpp
index f0f8e5fc..26beeab9 100644
--- a/examples/companion_radio/MyMesh.cpp
+++ b/examples/companion_radio/MyMesh.cpp
@@ -678,7 +678,7 @@ void MyMesh::onContactResponse(const ContactInfo &contact, const uint8_t *data,
   }
 }
 
-bool MyMesh::onContactPathRecv(ContactInfo& contact, uint8_t* in_path, uint8_t _in_path_len, uint8_t* out_path, uint8_t _out_path_len, uint8_t extra_type, uint8_t* extra, uint8_t extra_len) {
+bool MyMesh::onContactPathRecv(ContactInfo& contact, uint8_t* in_path, uint8_t in_path_len, uint8_t* out_path, uint8_t out_path_len, uint8_t extra_type, uint8_t* extra, uint8_t extra_len) {
   if (extra_type == PAYLOAD_TYPE_RESPONSE && extra_len > 4) {
     uint32_t tag;
     memcpy(&tag, extra, 4);
@@ -686,7 +686,7 @@ bool MyMesh::onContactPathRecv(ContactInfo& contact, uint8_t* in_path, uint8_t _
     if (tag == pending_discovery) {  // check for matching response tag)
       pending_discovery = 0;
 
-      if (in_path_len > MAX_PATH_SIZE || out_path_len > MAX_PATH_SIZE) {
+      if (!mesh::Packet::isValidPathLen(in_path_len) || !mesh::Packet::isValidPathLen(out_path_len)) {
         MESH_DEBUG_PRINTLN("onContactPathRecv, invalid path sizes: %d, %d", in_path_len, out_path_len);
       } else {
         int i = 0;
@@ -695,11 +695,9 @@ bool MyMesh::onContactPathRecv(ContactInfo& contact, uint8_t* in_path, uint8_t _
         memcpy(&out_frame[i], contact.id.pub_key, 6);
         i += 6; // pub_key_prefix
         out_frame[i++] = out_path_len;
-        memcpy(&out_frame[i], out_path, out_path_len);
-        i += out_path_len;
+        i += mesh::Packet::writePath(&out_frame[i], out_path, out_path_len);
         out_frame[i++] = in_path_len;
-        memcpy(&out_frame[i], in_path, in_path_len);
-        i += in_path_len;
+        i += mesh::Packet::writePath(&out_frame[i], in_path, in_path_len);
         // NOTE: telemetry data in 'extra' is discarded at present
 
         _serial->writeFrame(out_frame, i);
diff --git a/examples/simple_repeater/MyMesh.cpp b/examples/simple_repeater/MyMesh.cpp
index 7328f703..81c1dcb4 100644
--- a/examples/simple_repeater/MyMesh.cpp
+++ b/examples/simple_repeater/MyMesh.cpp
@@ -917,7 +917,7 @@ void MyMesh::sendSelfAdvertisement(int delay_millis, bool flood) {
   mesh::Packet *pkt = createSelfAdvert();
   if (pkt) {
     if (flood) {
-      sendFlood(pkt, delay_millis);   // TODO: which path_hash_size to use??
+      sendFlood(pkt, delay_millis, _prefs.path_hash_mode + 1);
     } else {
       sendZeroHop(pkt, delay_millis);
     }
diff --git a/examples/simple_room_server/MyMesh.cpp b/examples/simple_room_server/MyMesh.cpp
index 0b1d3a1b..06d9cc96 100644
--- a/examples/simple_room_server/MyMesh.cpp
+++ b/examples/simple_room_server/MyMesh.cpp
@@ -680,7 +680,7 @@ void MyMesh::sendSelfAdvertisement(int delay_millis, bool flood) {
   mesh::Packet *pkt = createSelfAdvert();
   if (pkt) {
     if (flood) {
-      sendFlood(pkt, delay_millis);  // TODO: which path_hash_size to use?
+      sendFlood(pkt, delay_millis, _prefs.path_hash_mode + 1);
     } else {
       sendZeroHop(pkt, delay_millis);
     }
diff --git a/examples/simple_sensor/SensorMesh.cpp b/examples/simple_sensor/SensorMesh.cpp
index fc9ef310..68fea474 100644
--- a/examples/simple_sensor/SensorMesh.cpp
+++ b/examples/simple_sensor/SensorMesh.cpp
@@ -261,7 +261,8 @@ void SensorMesh::sendAlert(const ClientInfo* c, Trigger* t) {
     if (c->out_path_len != OUT_PATH_UNKNOWN) {  // we have an out_path, so send DIRECT
       sendDirect(pkt, c->out_path, c->out_path_len);
     } else {
-      sendFlood(pkt);
+      unsigned long delay_millis = 0;
+      sendFlood(pkt, delay_millis, _prefs.path_hash_mode + 1);
     }
   }
   t->send_expiry = futureMillis(ALERT_ACK_EXPIRY_MILLIS);
@@ -567,7 +568,7 @@ void SensorMesh::onPeerDataRecv(mesh::Packet* packet, uint8_t type, int sender_i
             // let this sender know path TO here, so they can use sendDirect(), and ALSO encode the ACK
             mesh::Packet* path = createPathReturn(from->id, secret, packet->path, packet->path_len,
                                                   PAYLOAD_TYPE_ACK, (uint8_t *) &ack_hash, 4);
-            if (path) sendFlood(path, TXT_ACK_DELAY);
+            if (path) sendFlood(path, TXT_ACK_DELAY, packet->getPathHashSize());
           } else {
             sendAckTo(*from, ack_hash, packet->getPathHashSize());
           }
@@ -791,7 +792,7 @@ void SensorMesh::sendSelfAdvertisement(int delay_millis, bool flood) {
   mesh::Packet* pkt = createSelfAdvert();
   if (pkt) {
     if (flood) {
-      sendFlood(pkt, delay_millis);
+      sendFlood(pkt, delay_millis, _prefs.path_hash_mode + 1);
     } else {
       sendZeroHop(pkt, delay_millis);
     }
@@ -868,7 +869,8 @@ void SensorMesh::loop() {
 
   if (next_flood_advert && millisHasNowPassed(next_flood_advert)) {
     mesh::Packet* pkt = createSelfAdvert();
-    if (pkt) sendFlood(pkt);
+    unsigned long delay_millis = 0;
+    if (pkt) sendFlood(pkt, delay_millis, _prefs.path_hash_mode + 1);
 
     updateFloodAdvertTimer();   // schedule next flood advert
     updateAdvertTimer();   // also schedule local advert (so they don't overlap)
diff --git a/src/Packet.cpp b/src/Packet.cpp
index 0a75c2b3..9fd06395 100644
--- a/src/Packet.cpp
+++ b/src/Packet.cpp
@@ -10,14 +10,27 @@ Packet::Packet() {
   payload_len = 0;
 }
 
-uint8_t Packet::copyPath(uint8_t* dest, const uint8_t* src, uint8_t path_len) {
+bool Packet::isValidPathLen(uint8_t path_len) {
   uint8_t hash_count = path_len & 63;
   uint8_t hash_size = (path_len >> 6) + 1;
-  if (hash_count*hash_size > MAX_PATH_SIZE) {
+  if (hash_size == 4) return false;  // Reserved for future
+  return hash_count*hash_size <= MAX_PATH_SIZE;
+}
+
+size_t Packet::writePath(uint8_t* dest, const uint8_t* src, uint8_t path_len) {
+  uint8_t hash_count = path_len & 63;
+  uint8_t hash_size = (path_len >> 6) + 1;
+  size_t len = hash_count*hash_size;
+  if (len > MAX_PATH_SIZE) {
     MESH_DEBUG_PRINTLN("Packet::copyPath, invalid path_len=%d", (uint32_t)path_len);
     return 0;   // Error
   }
-  memcpy(dest, src, hash_count*hash_size);
+  memcpy(dest, src, len);
+  return len;
+}
+
+uint8_t Packet::copyPath(uint8_t* dest, const uint8_t* src, uint8_t path_len) {
+  if (writePath(dest, src, path_len) == 0) return 0;
   return path_len;
 }
 
diff --git a/src/Packet.h b/src/Packet.h
index b325fc1c..78619546 100644
--- a/src/Packet.h
+++ b/src/Packet.h
@@ -82,7 +82,9 @@ public:
   void setPathHashCount(uint8_t n) { path_len &= ~63; path_len |= n; }
   void setPathHashSizeAndCount(uint8_t sz, uint8_t n) { path_len = ((sz - 1) << 6) | (n & 63); }
 
-  static uint8_t copyPath(uint8_t* dest, const uint8_t* src, uint8_t path_len);
+  static uint8_t copyPath(uint8_t* dest, const uint8_t* src, uint8_t path_len);  // returns path_len
+  static size_t writePath(uint8_t* dest, const uint8_t* src, uint8_t path_len);  // returns byte length written
+  static bool isValidPathLen(uint8_t path_len);
 
   void markDoNotRetransmit() { header = 0xFF; }
   bool isMarkedDoNotRetransmit() const { return header == 0xFF; }
diff --git a/src/helpers/CommonCLI.cpp b/src/helpers/CommonCLI.cpp
index 263eb665..f2f961b9 100644
--- a/src/helpers/CommonCLI.cpp
+++ b/src/helpers/CommonCLI.cpp
@@ -63,7 +63,8 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
     file.read((uint8_t *)&_prefs->multi_acks, sizeof(_prefs->multi_acks));                         // 115
     file.read((uint8_t *)&_prefs->bw, sizeof(_prefs->bw));                                         // 116
     file.read((uint8_t *)&_prefs->agc_reset_interval, sizeof(_prefs->agc_reset_interval));         // 120
-    file.read(pad, 3);                                                                             // 121
+    file.read((uint8_t *)&_prefs->path_hash_mode, sizeof(_prefs->path_hash_mode));                 // 121
+    file.read(pad, 2);                                                                             // 122
     file.read((uint8_t *)&_prefs->flood_max, sizeof(_prefs->flood_max));                           // 124
     file.read((uint8_t *)&_prefs->flood_advert_interval, sizeof(_prefs->flood_advert_interval));   // 125
     file.read((uint8_t *)&_prefs->interference_threshold, sizeof(_prefs->interference_threshold)); // 126
@@ -95,6 +96,7 @@ void CommonCLI::loadPrefsInt(FILESYSTEM* fs, const char* filename) {
     _prefs->tx_power_dbm = constrain(_prefs->tx_power_dbm, -9, 30);
     _prefs->multi_acks = constrain(_prefs->multi_acks, 0, 1);
     _prefs->adc_multiplier = constrain(_prefs->adc_multiplier, 0.0f, 10.0f);
+    _prefs->path_hash_mode = constrain(_prefs->path_hash_mode, 0, 2);   // NOTE: mode 3 reserved for future
 
     // sanitise bad bridge pref values
     _prefs->bridge_enabled = constrain(_prefs->bridge_enabled, 0, 1);
@@ -147,7 +149,8 @@ void CommonCLI::savePrefs(FILESYSTEM* fs) {
     file.write((uint8_t *)&_prefs->multi_acks, sizeof(_prefs->multi_acks));                         // 115
     file.write((uint8_t *)&_prefs->bw, sizeof(_prefs->bw));                                         // 116
     file.write((uint8_t *)&_prefs->agc_reset_interval, sizeof(_prefs->agc_reset_interval));         // 120
-    file.write(pad, 3);                                                                             // 121
+    file.write((uint8_t *)&_prefs->path_hash_mode, sizeof(_prefs->path_hash_mode));                 // 121
+    file.write(pad, 2);                                                                             // 122
     file.write((uint8_t *)&_prefs->flood_max, sizeof(_prefs->flood_max));                           // 124
     file.write((uint8_t *)&_prefs->flood_advert_interval, sizeof(_prefs->flood_advert_interval));   // 125
     file.write((uint8_t *)&_prefs->interference_threshold, sizeof(_prefs->interference_threshold)); // 126
@@ -325,6 +328,8 @@ void CommonCLI::handleCommand(uint32_t sender_timestamp, const char* command, ch
           sp++;
         }
         *reply = 0;  // set null terminator
+      } else if (memcmp(config, "path.hash.mode", 14) == 0) {
+        sprintf(reply, "> %d", (uint32_t)_prefs->path_hash_mode);
       } else if (memcmp(config, "tx", 2) == 0 && (config[2] == 0 || config[2] == ' ')) {
         sprintf(reply, "> %d", (int32_t) _prefs->tx_power_dbm);
       } else if (memcmp(config, "freq", 4) == 0) {
@@ -556,6 +561,16 @@ void CommonCLI::handleCommand(uint32_t sender_timestamp, const char* command, ch
         *dp = 0;
         savePrefs();
         strcpy(reply, "OK");
+      } else if (memcmp(config, "path.hash.mode ", 15) == 0) {
+        config += 15;
+        uint8_t mode = atoi(config);
+        if (mode < 3) {
+          _prefs->path_hash_mode = mode;
+          savePrefs();
+          strcpy(reply, "OK");
+        } else {
+          strcpy(reply, "Error, must be 0,1, or 2");
+        }
       } else if (memcmp(config, "tx ", 3) == 0) {
         _prefs->tx_power_dbm = atoi(&config[3]);
         savePrefs();
diff --git a/src/helpers/CommonCLI.h b/src/helpers/CommonCLI.h
index 146e1c6e..1e454ec2 100644
--- a/src/helpers/CommonCLI.h
+++ b/src/helpers/CommonCLI.h
@@ -52,6 +52,7 @@ struct NodePrefs { // persisted to file
   uint32_t discovery_mod_timestamp;
   float adc_multiplier;
   char owner_info[120];
+  uint8_t path_hash_mode;   // which path mode to use when sending
 };
 
 class CommonCLICallbacks {