diff --git a/lib/spack/spack/build_systems/r.py b/lib/spack/spack/build_systems/r.py
index f8553c476b7..ac57672a398 100644
--- a/lib/spack/spack/build_systems/r.py
+++ b/lib/spack/spack/build_systems/r.py
@@ -84,6 +84,7 @@ def install(self, spec, prefix):
         config_vars = self.configure_vars()
 
         args = [
+            '--vanilla',
             'CMD',
             'INSTALL'
         ]