diff --git a/MANUAL.txt b/MANUAL.txt
index 0ad2e9220..3fe34ad8e 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -861,7 +861,7 @@ Options affecting specific writers {.options}
 
 :   Use only ASCII characters in output. Currently supported for XML
     and HTML formats (which use entities instead of UTF-8 when this
-    option is selected), CommonMark and Markdown (which uses
+    option is selected), CommonMark, gfm, and Markdown (which use
     entities), roff ms (which use hexadecimal escapes), and to a
     limited degree LaTeX (which uses standard commands for accented
     characters when possible). roff man output uses ASCII by default.