diff --git a/src/global.h b/src/global.h
index 2dc92a0e..9afe797f 100755
--- a/src/global.h
+++ b/src/global.h
@@ -107,7 +107,8 @@ LED bar:      lbr
 #define SYSTEM_SAMPLE_RATE_HZ           48000 // Hz
 
 // System block size, this is the block size on which the audio coder works.
-// All other block sizes must be a multiple of this size
+// All other block sizes must be a multiple of this size.
+// Note that the UpdateAutoSetting() function assumes a value of 128.
 #define SYSTEM_FRAME_SIZE_SAMPLES       128
 
 #define SYSTEM_BLOCK_DURATION_MS_FLOAT  \