diff --git a/CMake/vtkOpenGLOptions.cmake b/CMake/vtkOpenGLOptions.cmake
index c97dec3a91..b3c67e5bac 100644
--- a/CMake/vtkOpenGLOptions.cmake
+++ b/CMake/vtkOpenGLOptions.cmake
@@ -13,9 +13,11 @@ cmake_dependent_option(VTK_USE_COCOA "Use Cocoa for VTK render windows" ON
 mark_as_advanced(VTK_USE_COCOA)
 
 set(default_use_x OFF)
-if(UNIX AND NOT ANDROID AND NOT APPLE AND NOT APPLE_IOS AND NOT CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
+if(UNIX AND NOT ANDROID AND NOT APPLE_IOS AND NOT CMAKE_SYSTEM_NAME STREQUAL "Emscripten")
   set(default_use_x ON)
 endif()
+# Note: On macOS, X11 can be enabled manually with -DVTK_USE_COCOA=OFF -DVTK_USE_X=ON
+# This requires XQuartz and optionally Mesa for GL 3.3+ features via llvmpipe
 option(VTK_USE_X "Use X for VTK render windows" "${default_use_x}")
 mark_as_advanced(VTK_USE_X)