diff --git a/gnu/packages/ncdu.scm b/gnu/packages/ncdu.scm
index a623cd5373..6f541878fc 100644
--- a/gnu/packages/ncdu.scm
+++ b/gnu/packages/ncdu.scm
@@ -71,7 +71,9 @@ ncurses installed.")
      (list
        #:make-flags
        #~(list (string-append "PREFIX=" #$output)
-               (string-append "CC=" #$(cc-for-target)))
+               (string-append "CC=" #$(cc-for-target))
+               ;; XXX By default, zig builds with -march=native!
+               (string-append "ZIG_FLAGS=-Drelease-fast -Dcpu=baseline"))
        #:phases
        #~(modify-phases %standard-phases
            (delete 'configure)      ; No configure script.