diff --git a/libstdc++-v3/doc/html/manual/api.html b/libstdc++-v3/doc/html/manual/api.html
index 1849e115936..70889a583f9 100644
--- a/libstdc++-v3/doc/html/manual/api.html
+++ b/libstdc++-v3/doc/html/manual/api.html
@@ -405,6 +405,13 @@ now defaults to zero.
   for C++20 mode. The removed functionality has been provided by
   <code class="classname">std::allocator_traits</code> since C++11 and that should
   be used instead.
+</p><p>
+  The type of the <code class="classname">std::iterator</code> base class of
+  <code class="classname">std::istreambuf_iterator</code> was changed to be
+  consistent for all <code class="option">-std</code> modes.
+  Before GCC 10.1 the base class had one type in C++98 mode and a
+  different type in C++11 and later modes. The type in C++98 mode
+  was changed to be the same as for C++11 and later.
 </p><p>
   Experimental C++2a support improved, with new headers
   <code class="filename">&lt;concepts&gt;</code>,
diff --git a/libstdc++-v3/doc/xml/manual/evolution.xml b/libstdc++-v3/doc/xml/manual/evolution.xml
index 38f11b0300d..55b8903baff 100644
--- a/libstdc++-v3/doc/xml/manual/evolution.xml
+++ b/libstdc++-v3/doc/xml/manual/evolution.xml
@@ -972,6 +972,15 @@ now defaults to zero.
   be used instead.
 </para>
 
+<para>
+  The type of the <classname>std::iterator</classname> base class of
+  <classname>std::istreambuf_iterator</classname> was changed to be
+  consistent for all <option>-std</option> modes.
+  Before GCC 10.1 the base class had one type in C++98 mode and a
+  different type in C++11 and later modes. The type in C++98 mode
+  was changed to be the same as for C++11 and later.
+</para>
+
 <para>
   Experimental C++2a support improved, with new headers
   <filename class="headerfile">&lt;concepts&gt;</filename>,