diff --git a/types/block.go b/types/block.go
index c8cdf81a9..17e257b9d 100644
--- a/types/block.go
+++ b/types/block.go
@@ -169,7 +169,7 @@ type Header struct {
 }
 
 // Hash returns the hash of the header.
-// NOTE: hash is nil if required fields are missing.
+// Returns nil if ValidatorHash is missing.
 func (h *Header) Hash() data.Bytes {
 	if len(h.ValidatorsHash) == 0 {
 		return nil