diff --git a/README.adoc b/README.adoc
index b1a077e..db23b5c 100644
--- a/README.adoc
+++ b/README.adoc
@@ -37,6 +37,8 @@ Rather, it's intended to be used on AsciiDoc documents that are written with con
 
 == Supported syntax
 
+In order for downdoc to convert an AsciiDoc document, it must have lines that end with LF (`\n`), not CRLF (`\r\n`).
+
 Here's a rough list of the AsciiDoc syntax that downdoc current handles:
 
 * document title (atx-style only; Markdown-style headings not supported)