diff --git a/guix/build/syscalls.scm b/guix/build/syscalls.scm
index 5aae1530f..e108d6169 100644
--- a/guix/build/syscalls.scm
+++ b/guix/build/syscalls.scm
@@ -462,7 +462,9 @@ the returned procedure is called."
 (define UMOUNT_NOFOLLOW 8)
 
 (define mount
-  (let ((proc (syscall->procedure int "mount" `(* * * ,unsigned-long *))))
+  (let ((proc (if (module-defined? the-scm-module 'mount)
+                  (module-ref the-scm-module 'mount)
+                  (syscall->procedure int "mount" `(* * * ,unsigned-long *)))))
     (lambda* (source target type #:optional (flags 0) options
                      #:key (update-mtab? #f))
       "Mount device SOURCE on TARGET as a file system TYPE.  Optionally, FLAGS