diff --git a/milli/src/update/facet/mod.rs b/milli/src/update/facet/mod.rs
index a6d8c3d60..a5d527282 100644
--- a/milli/src/update/facet/mod.rs
+++ b/milli/src/update/facet/mod.rs
@@ -68,6 +68,8 @@ bulk method is faster when a large part of the database is modified. Empirically
 it takes 50x more time to incrementally add N facet values to an existing database than it is to
 construct a database of N facet values. This is the heuristic that is used to choose between the
 two methods.
+
+Related PR: https://github.com/meilisearch/milli/pull/619
 */
 
 pub const FACET_MAX_GROUP_SIZE: u8 = 8;