diff --git a/MANUAL.markdown b/MANUAL.markdown
index 36e656f1c..e88c3264b 100644
--- a/MANUAL.markdown
+++ b/MANUAL.markdown
@@ -75,7 +75,10 @@ with the cabal-install tool:
 
     - `-fwebyesod` - builds a newer version of the [web](#web) command (requires ghc 6.12).
 
-    - `-fchart` builds the [chart](#chart) command.
+    - `-fchart` builds the [chart](#chart) command. This requires
+      additional GTK/GHC integration libraries (on ubuntu: `apt-get
+      install libghc6-gtk-dev`) and possibly other things - see the
+      [gtk2hs install docs](http://code.haskell.org/gtk2hs/INSTALL).
 
 If you have any trouble, proceed at once to [Troubleshooting](#troubleshooting) for help!