diff --git a/gnu/system.scm b/gnu/system.scm
index 6f795d6292..bb7e8531ee 100644
--- a/gnu/system.scm
+++ b/gnu/system.scm
@@ -250,7 +250,7 @@ (define device-sexp->device
                        rest ...)
      (boot-parameters
       (label label)
-      (root-device (device->sexp root))
+      (root-device (device-sexp->device root))
 
       (bootloader-name
        (match (assq 'bootloader-name rest)