diff --git a/var/spack/repos/builtin/packages/eq-r/package.py b/var/spack/repos/builtin/packages/eq-r/package.py
index 76c10c82c5e..720e2bed8f9 100644
--- a/var/spack/repos/builtin/packages/eq-r/package.py
+++ b/var/spack/repos/builtin/packages/eq-r/package.py
@@ -46,7 +46,7 @@ def configure_args(self):
         if not os.path.exists(r_location):
             rscript = which('Rscript')
             if rscript is not None:
-                r_location = rscript('-e', 'cat(R.home())')
+                r_location = rscript('-e', 'cat(R.home())', output=str)
             else:
                 msg = 'couldn\'t locate Rscript on your PATH'
                 raise RuntimeError(msg)