diff --git a/ChangeLog b/ChangeLog
index f76e242d..0a0bdb65 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2011-10-22  Nicolas François  <nicolas.francois@centraliens.net>
+
+	* man/su.1.xml: Document that su -c does not providea controlling
+	terminal.
+
 2011-10-18  Nicolas François  <nicolas.francois@centraliens.net>
 
 	* src/newusers.c: Fix typo.
diff --git a/man/su.1.xml b/man/su.1.xml
index b4ac203d..02222d66 100644
--- a/man/su.1.xml
+++ b/man/su.1.xml
@@ -137,6 +137,13 @@
 	    Specify a command that will be invoked by the shell using its
 	    <option>-c</option>.
 	  </para>
+	  <para>
+	    The executed command will have no controlling terminal. This
+	    option cannot be used to execute interractive programs which
+	    need a controlling TTY.
+	    <!-- This avoids TTY hijacking when su is used to lower
+	         privileges -->
+	  </para>
 	</listitem>
       </varlistentry>
       <varlistentry>