--- a/gnu/build/linux-boot.scm
+++ b/gnu/build/linux-boot.scm
@@ -534,10 +534,13 @@ upon error."
             ;; The "--root=SPEC" kernel command-line option always provides a
             ;; string, but the string can represent a device, a UUID, or a
             ;; label.  So check for all three.

Nitpick: Comment above it is now outdated ;)