diff --git a/coreutils/cksum.c b/coreutils/cksum.c
index 7a37e6add..53fb87a78 100644
--- a/coreutils/cksum.c
+++ b/coreutils/cksum.c
@@ -38,6 +38,7 @@ int cksum_main(int argc UNUSED_PARAM, char **argv)
 
 #define read_buf bb_common_bufsiz1
 		while ((bytes_read = safe_read(fd, read_buf, sizeof(read_buf))) > 0) {
+			length += bytes_read;
 			crc = crc32_block_endian1(crc, read_buf, bytes_read, crc32_table);
 		}
 		close(fd);