diff --git a/flashrom.c b/flashrom.c
index fffedd6..64a6835 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -407,7 +407,8 @@
 }
 
 /**
- * @cmpbuf	buffer to compare against
+ * @cmpbuf	buffer to compare against, cmpbuf[0] is expected to match the
+		flash content at location start
  * @start	offset to the base address of the flash chip
  * @len		length of the verified area
  * @message	string to print in the "FAILED" message