diff --git a/src/MeshCore.h b/src/MeshCore.h
index 2db1d4c3ec..af5c2efeed 100644
--- a/src/MeshCore.h
+++ b/src/MeshCore.h
@@ -3,7 +3,7 @@
 #include <stdint.h>
 #include <math.h>
 
-#define MAX_HASH_SIZE        8
+#define MAX_HASH_SIZE        4
 #define PUB_KEY_SIZE        32
 #define PRV_KEY_SIZE        64
 #define SEED_SIZE           32
diff --git a/src/helpers/SimpleMeshTables.h b/src/helpers/SimpleMeshTables.h
index 2f8af52af1..1ddba94064 100644
--- a/src/helpers/SimpleMeshTables.h
+++ b/src/helpers/SimpleMeshTables.h
@@ -12,7 +12,7 @@
 class SimpleMeshTables : public mesh::MeshTables {
   uint8_t _hashes[MAX_PACKET_HASHES*MAX_HASH_SIZE];
   int _next_idx;
-  uint32_t _acks[MAX_PACKET_ACKS];
+  uint8_t _acks[MAX_PACKET_ACKS*MAX_HASH_SIZE];
   int _next_ack_idx;
   uint32_t _direct_dups, _flood_dups;
 
@@ -42,8 +42,8 @@ class SimpleMeshTables : public mesh::MeshTables {
 
   bool hasSeen(const mesh::Packet* packet) override {
     if (packet->getPayloadType() == PAYLOAD_TYPE_ACK) {
-      uint32_t ack;
-      memcpy(&ack, packet->payload, 4);
+      uint8_t ack;
+      memcpy(&ack, packet->payload, MAX_HASH_SIZE);
       for (int i = 0; i < MAX_PACKET_ACKS; i++) {
         if (ack == _acks[i]) { 
           if (packet->isRouteDirect()) {
@@ -82,8 +82,8 @@ class SimpleMeshTables : public mesh::MeshTables {
 
   void clear(const mesh::Packet* packet) override {
     if (packet->getPayloadType() == PAYLOAD_TYPE_ACK) {
-      uint32_t ack;
-      memcpy(&ack, packet->payload, 4);
+      uint8_t ack;
+      memcpy(&ack, packet->payload, MAX_HASH_SIZE);
       for (int i = 0; i < MAX_PACKET_ACKS; i++) {
         if (ack == _acks[i]) { 
           _acks[i] = 0;