diff --git a/doc/cc65.sgml b/doc/cc65.sgml
index 86b61ae4f..601e364ea 100644
--- a/doc/cc65.sgml
+++ b/doc/cc65.sgml
@@ -814,6 +814,14 @@ This cc65 version has some extensions to the ISO C standard.
         In the jump table, no expressions are supported. The array index
         used in the goto must be a simple variable or a constant.
 
+<item>  Binary literals, a C++14 feature and a GCC C extension, are accepted.
+        They can be disabled with the <tt><ref id="option--standard"
+        name="--standard"></tt> option.
+
+        <tscreen><verb>
+        unsigned char foo = 0b101; // sets it to 5
+        </verb></tscreen>
+
 </itemize>
 <p>