diff --git a/main/db_esp_now.c b/main/db_esp_now.c
index 128d56c..af7b7dc 100644
--- a/main/db_esp_now.c
+++ b/main/db_esp_now.c
@@ -544,7 +544,7 @@ esp_err_t db_espnow_init() {
     if (!esp_now_is_peer_exist(BROADCAST_MAC)) ESP_ERROR_CHECK(esp_now_add_peer(&peer));
 
     /* Limit payload size to the max we can do */
-    if (DB_TRANS_BUF_SIZE > DB_ESPNOW_PAYLOAD_MAXSIZE) {
+    if (DB_TRANS_BUF_SIZE > DB_ESPNOW_PAYLOAD_MAXSIZE || DB_TRANS_BUF_SIZE < 1) {
         DB_TRANS_BUF_SIZE = DB_ESPNOW_PAYLOAD_MAXSIZE;
     } else {
         // all good
diff --git a/main/http_server.c b/main/http_server.c
index ae72389..3f296d9 100644
--- a/main/http_server.c
+++ b/main/http_server.c
@@ -183,9 +183,18 @@ static esp_err_t settings_post_handler(httpd_req_t *req) {
     }
 
     json = cJSON_GetObjectItem(root, "trans_pack_size");
-    if (json) DB_TRANS_BUF_SIZE = json->valueint;
+    if (json && json->valueint > 0 && json->valueint < 1024) {
+        DB_TRANS_BUF_SIZE = json->valueint;
+    } else {
+        ESP_LOGE(REST_TAG, "Settings change: trans_pack_size is out of range (1-1024): %i", json->valueint);
+    }
+
     json = cJSON_GetObjectItem(root, "serial_timeout");
-    if (json) DB_SERIAL_READ_TIMEOUT_MS = json->valueint;
+    if (json && json->valueint > 0) {
+        DB_SERIAL_READ_TIMEOUT_MS = json->valueint;
+    } else {
+        ESP_LOGE(REST_TAG,"Serial read timeout must be >0 - ignoring");
+    }
     json = cJSON_GetObjectItem(root, "tx_pin");
     if (json) DB_UART_PIN_TX = json->valueint;
     json = cJSON_GetObjectItem(root, "rx_pin");