diff --git a/config.h b/config.h
index 494e4f0..ad8b87c 100644
--- a/config.h
+++ b/config.h
@@ -1,6 +1,7 @@
 #ifndef CONFIG_H
 #define CONFIG_H
 
-//#define F_CPU 1600000UL
+// This is passed as a compiler flag (CFLAGS += -DF_CPU=16000000UL)
+// #define F_CPU 1600000UL
 
 #endif // CONFIG_H