diff --git a/README.adoc b/README.adoc
index 13e37f7..240b382 100644
--- a/README.adoc
+++ b/README.adoc
@@ -86,10 +86,11 @@ If you get the error message that `add-apt-repository` was not found, install
 * Optional
   ** Tests: link:{uri-catch}[Catch] (tested: 2.13 / 1.10)
 
-==== Install dependencies in Debian or Ubuntu
+===== Install dependencies in Debian or Ubuntu
 
 Or distributions that are derived from Debian or Ubuntu. You will need at least
-Debian buster or Ubuntu bionic.
+Debian buster (10) or Ubuntu focal (20.04), unless you install a newer version
+of CMake.
 
 [source,shell]
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