diff --git a/winsup/doc/ChangeLog b/winsup/doc/ChangeLog
index c49e3b474..4cea1192a 100644
--- a/winsup/doc/ChangeLog
+++ b/winsup/doc/ChangeLog
@@ -1,3 +1,9 @@
+2013-04-24  Corinna Vinschen  <corinna@vinschen.de>
+	    Christian Franke  <Christian.Franke@t-online.de>
+
+	* faq-programming.xml (faq.programming.64bitporting): Mention the
+	-Wformat and -Wall gcc options.
+
 2013-04-24  Corinna Vinschen  <corinna@vinschen.de>
 
 	* faq-programming.xml (faq.programming.64bitporting): New FAQ entry.
diff --git a/winsup/doc/faq-programming.xml b/winsup/doc/faq-programming.xml
index c46e05f18..8a1bb962b 100644
--- a/winsup/doc/faq-programming.xml
+++ b/winsup/doc/faq-programming.xml
@@ -115,7 +115,11 @@ datatypes when the AMD64 CPU was new.</para>
     printf ("%d %ld\n", l, i);
 </screen>
 
-may not print what you think it should.
+may not print what you think it should.  Enable the gcc options -Wformat or
+-Wall, which warn about type mismatches in printf/scanf functions.
+
+<note>Using -Wall (optionally with -Werror to drive the point home) makes a
+lot of sense in general, not only when porting code to a new platform.</note>
 </para></listitem>
 
 <listitem><para>