diff --git a/doc/asdf.texinfo b/doc/asdf.texinfo
index 96da04eaa477096f5d6e7a8fd2b41999298cf735..e4ec528e2b1df34c217073c32bb5168e39a27493 100644
--- a/doc/asdf.texinfo
+++ b/doc/asdf.texinfo
@@ -1011,6 +1011,7 @@ other-component-type := symbol-by-name (@pxref{The defsystem grammar,,Component
 dependency-def := simple-component-name
                | ( :feature @var{feature-expression} dependency-def )
                | ( :version simple-component-name version-specifier )
+               | ( :require module-name )
 
 # ``dependency'' is used in :in-order-to, as opposed to
 # ``dependency-def''
@@ -1218,6 +1219,11 @@ where significant API incompatibilities are signaled by an increased major numbe
 
 @xref{Common attributes of components}.
 
+@subsection Require
+@cindex :require dependencies
+
+Use the implementation's own @code{require} to load the @var{module-name}.
+
 
 @subsection Using logical pathnames
 @cindex logical pathnames