diff --git a/src/image/gif/reader.go b/src/image/gif/reader.go
index e580ab049e..9e8268c86f 100644
--- a/src/image/gif/reader.go
+++ b/src/image/gif/reader.go
@@ -116,7 +116,7 @@ type decoder struct {
 // consumed when checking that the blockReader is exhausted.
 //
 // To avoid the allocation of a bufio.Reader for the lzw Reader, blockReader
-// implements io.ReadByte and buffers blocks into the decoder's "tmp" buffer.
+// implements io.ByteReader and buffers blocks into the decoder's "tmp" buffer.
 type blockReader struct {
 	d    *decoder
 	i, j uint8 // d.tmp[i:j] contains the buffered bytes