diff --git a/var/spack/repos/builtin/packages/root/package.py b/var/spack/repos/builtin/packages/root/package.py
index 3f38bdac85e..5fa20aa4b7b 100644
--- a/var/spack/repos/builtin/packages/root/package.py
+++ b/var/spack/repos/builtin/packages/root/package.py
@@ -428,7 +428,7 @@ def cmake_args(self):
             define('fail-on-missing', True),
             define_from_variant('fortran'),
             define_from_variant('gminimal'),
-            define('gnuinstall', False),
+            define('gnuinstall', True),
             define('libcxx', False),
             define('pch', True),
             define('roottest', False),