Index: avogadro-1.1.1/CMakeLists.txt
===================================================================
--- avogadro-1.1.1.orig/CMakeLists.txt
+++ avogadro-1.1.1/CMakeLists.txt
@@ -225,7 +225,7 @@
 
 find_package(Qt4 4.6.0 REQUIRED) # find and setup Qt4 for this project
 find_package(OpenGL REQUIRED) # find and setup OpenGL
-find_package(X11) # find and setup X11 (not required for Mac and Windows)
+find_package(X11 REQUIRED) # find and setup X11
 find_package(Linguist) # find and setup Linguist
 if(NOT Linguist_FOUND)
   message(WARNING " Qt4 Linguist not found, please install it if you want Avogadro translations")