diff --git a/src/main.cpp b/src/main.cpp
index bc2250c..12a37d1 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -399,7 +399,7 @@ static void factoryReset(bool clearWifi) {
   Serial.printf("[BOOT] factory reset triggered (clearWifi=%d)!\n", clearWifi);
 
   strlcpy(hostname, HOSTNAME_DEFAULT, sizeof(hostname));
-  hostnameParam.setValue(hostname, strlen(hostname));
+  hostnameParam.setValue(hostname, sizeof(hostname) - 1);
 
   authCfg.enabled = false;
   authCfg.pass[0] = '\0';
@@ -455,7 +455,7 @@ void setup() {
   LittleFS.begin(true);
 
   loadConfig();
-  hostnameParam.setValue(hostname, strlen(hostname));
+  hostnameParam.setValue(hostname, sizeof(hostname) - 1);
 
   int resetCount = incrementResetCount();