diff --git a/README.adoc b/README.adoc
index 240b382..d282741 100644
--- a/README.adoc
+++ b/README.adoc
@@ -55,7 +55,8 @@ sudo emerge -a app-text/epubgrep
 === Debian and Ubuntu
 
 This repository works for Debian buster (10) and Ubuntu focal (20.04). It _may_
-work for other versions, I have not tested it.
+work for other versions, I have not tested it. It does not work for Ubuntu
+bionic (18.04).
 
 [source,shell]
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