diff --git a/modules/doc/install.rst b/modules/doc/install.rst
index 9d59fbed59e855b02a74e94f33d735e922738174..28b34d60e5b8789cbd868eb10de384a1d0874c6b 100644
--- a/modules/doc/install.rst
+++ b/modules/doc/install.rst
@@ -226,6 +226,10 @@ can influence it.
   * Usually, you will receive errors for those variables when executing `cmake`
     and set them accordingly as needed.
 
+* `OPENGLPREFERENCE_LEGACY` switches the GL implementation to be used by OpenGL.
+  The default is what should be used on modern systems. But since there are some
+  reports on the internet claiming that the default does not work everywhere,
+  this switch enables the usage of the legacy implementation of GL.
   
 Build Options
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^