diff --git a/code/espurna/config/all.h b/code/espurna/config/all.h
index d734e0ba..2494890c 100644
--- a/code/espurna/config/all.h
+++ b/code/espurna/config/all.h
@@ -28,6 +28,7 @@
 #include "arduino.h"
 #include "hardware.h"
 #include "defaults.h"
+#include "deprecated.h"
 #include "general.h"
 #include "dependencies.h"
 #include "debug.h"
diff --git a/code/espurna/config/deprecated.h b/code/espurna/config/deprecated.h
new file mode 100644
index 00000000..a8a99508
--- /dev/null
+++ b/code/espurna/config/deprecated.h
@@ -0,0 +1,9 @@
+#pragma once
+
+// 1.13.3 added TELNET_PASSWORD build-only flag
+// 1.13.4 replaces it with TELNET_AUTHENTICATION runtime setting default
+// TODO warning should be removed eventually
+#ifdef TELNET_PASSWORD
+#warning TELNET_PASSWORD is deprecated! Please replace it with TELNET_AUTHENTICATION
+#define TELNET_AUTHENTICATION TELNET_PASSWORD
+#endif