diff --git a/src/sensesp.h b/src/sensesp.h
index 8c0591007..26c573083 100644
--- a/src/sensesp.h
+++ b/src/sensesp.h
@@ -12,6 +12,10 @@
     "ESP8266 isn't supported by SensESP version 2. To compile an existing project, add @^1.0.0 to the SensESP depdenency in platformio.ini."
 #endif
 
+#ifndef CORE_DEBUG_LEVEL
+#error "SensESP v3 requires CORE_DEBUG_LEVEL to be defined. See https://signalk.org/SensESP/pages/migration/."
+#endif
+
 namespace sensesp {
 
 // Typically, pulling a namespace into another is something to be avoided,