diff --git a/FileId.md b/FileId.md
index 0173e7a..85b6772 100644
--- a/FileId.md
+++ b/FileId.md
@@ -1,4 +1,4 @@
-The "file id" is a tagged hash of the plaintext of the file to be uploaded. It is used as the final end-to-end integrity check of the user's data, use to detect any problems in the entire processing chain: corrupted shares, broken erasure coding, the wrong decryption key.
+The "file id" is a [TaggedHash](TaggedHash) of the plaintext of the file to be uploaded. It is used as the final end-to-end integrity check of the user's data, use to detect any problems in the entire processing chain: corrupted shares, broken erasure coding, the wrong decryption key.
 
 Because it is a hash of the entire file, download-time verification cannot be completed until the entire file has been retrieved. For large files that are being streamed, this only provides an after-the-fact check: "sorry, but the data that you just finished downloading and viewing was corrupted".