diff --git a/README.7 b/README.7
index aa05fac..0261d3e 100644
--- a/README.7
+++ b/README.7
@@ -1,4 +1,4 @@
-.Dd September  1, 2020
+.Dd November 11, 2020
 .Dt README 7
 .Os "Causal Agency"
 .\" To view this file, run: man ./README.7
@@ -37,6 +37,11 @@ color generation based on usernames
 remains stable across nick changes.
 Mentions of users in messages are colored.
 .It
+Topic diffing:
+the modified portion
+of a channel topic change
+is highlighted.
+.It
 Ignore:
 visibility of filtered messages
 can be toggled.