diff --git a/lib/framework/APSettingsService.h b/lib/framework/APSettingsService.h
index 998f290f..fc0d02f6 100644
--- a/lib/framework/APSettingsService.h
+++ b/lib/framework/APSettingsService.h
@@ -9,6 +9,9 @@
 #include <DNSServer.h>
 #include <IPAddress.h>
 
+#define CHECK_LEN(s, min_len, max_len) \
+  static_assert(min_len <= sizeof(s) && sizeof(s) <= max_len, #s " should have " #min_len "-" #max_len " characters.")
+
 #ifndef FACTORY_AP_PROVISION_MODE
 #define FACTORY_AP_PROVISION_MODE AP_MODE_DISCONNECTED
 #endif
@@ -17,10 +20,14 @@
 #define FACTORY_AP_SSID "ESP8266-React-#{unique_id}"
 #endif
 
+CHECK_LEN(FACTORY_AP_SSID, 1, 64);
+
 #ifndef FACTORY_AP_PASSWORD
 #define FACTORY_AP_PASSWORD "esp-react"
 #endif
 
+CHECK_LEN(FACTORY_AP_PASSWORD, 8, 64);
+
 #ifndef FACTORY_AP_LOCAL_IP
 #define FACTORY_AP_LOCAL_IP "192.168.4.1"
 #endif