diff --git a/.git-blame-ignore-revs b/.git-blame-ignore-revs
index 0eb30218f..12458ce99 100644
--- a/.git-blame-ignore-revs
+++ b/.git-blame-ignore-revs
@@ -1,2 +1,4 @@
 # git config blame.ignoreRevsFile .git-blame-ignore-revs
 40e0cdb95ff31b81212109fada6e0ff93b6eefee
+# Upgrade to OCamlformat 0.27.0-preview1
+8cf9d4d43132f025af0ad4dbc5bc852f162f692f