diff --git a/DOCS/documentation.html b/DOCS/documentation.html
index 805ed38183..ee0ba05aac 100644
--- a/DOCS/documentation.html
+++ b/DOCS/documentation.html
@@ -362,7 +362,8 @@ into your config file, <CODE>$HOME/.mplayer/config</CODE> .</P>
 
 <P><B><A NAME=1.4>1.4. What about the GUI?</A></B></P>
 
-<P>The GUI needs GTK (it isn't GTK, but the panels are), so gtk (and it's devel stuff) has to be installed.
+<P>The GUI needs GTK (it isn't GTK, but the panels are). The skins are stored
+in PNG format, so gtk, libpng (and their devel stuff) has to be installed.
 You can build it by specifying <CODE>--enable-gui</CODE> during ./configure .
 Then, to turn on GUI mode, you either
 <UL>