diff --git a/computer-graphics.org b/computer-graphics.org
index 96e5951..67cd7e1 100644
--- a/computer-graphics.org
+++ b/computer-graphics.org
@@ -1081,7 +1081,7 @@ Install OpenGL development dependencies on Ubuntu or Debian-like
 distributions:
 
 #+BEGIN_SRC sh
-   $ sudo apt-get install -y libgl1-mesa-dev libglu1-mesa-dev freeglut3-dev  libgl1-mesa-dev libxrandr-dev
+   $ sudo apt-get install -y libgl1-mesa-dev libglu1-mesa-dev freeglut3-dev libgl1-mesa-dev libxrandr-dev
    $ sudo apt-get install -y libxinerama-dev libxcursor-dev libxi-dev
 #+END_SRC