diff --git a/rlp/encbuffer.go b/rlp/encbuffer.go
index 145c2e658b130..0e200a9a33bbe 100644
--- a/rlp/encbuffer.go
+++ b/rlp/encbuffer.go
@@ -249,6 +249,9 @@ func (r *encReader) next() []byte {
 }
 
 // EncoderBuffer is a buffer for incremental encoding.
+//
+// The zero value is NOT ready for use. To get a usable buffer,
+// create it using NewEncoderBuffer or call Reset.
 type EncoderBuffer struct {
 	buf *encBuffer
 	dst io.Writer