diff --git a/racket/src/expander/extract/flatten.rkt b/racket/src/expander/extract/flatten.rkt
index a905ba94e0..df8ced8c09 100644
--- a/racket/src/expander/extract/flatten.rkt
+++ b/racket/src/expander/extract/flatten.rkt
@@ -150,8 +150,11 @@
     (cond
      [(find-knot-tying-alternate knot-ties lnk (car external+local) linklets)
       => (lambda (alt-lnk)
-           (unless (eq? alt-lnk 'ignore)
-             (add-subst! alt-lnk external+local knot-ties)))]
+           (if (eq? alt-lnk 'ignore)
+               ;; Map to original name:
+               (hash-set! substs (cdr external+local) (car external+local))
+               ;; Map to alt-link:
+               (add-subst! alt-lnk external+local knot-ties)))]
      [else
       (hash-set! substs
                  (cdr external+local)
@@ -180,7 +183,15 @@
                  'ignore]
                 [else
                  (define alt-lnk (link alt-path 0))
-                 (define li (hash-ref linklets alt-lnk))
+                 (define li (hash-ref linklets alt-lnk
+                                      (lambda ()
+                                        (error 'flatten
+                                               (string-append "module for knot tying is not part"
+                                                              " of the flattened module's implementation\n"
+                                                              "  module: ~a\n"
+                                                              "  attempted redirect for: ~a")
+                                               (link-name alt-lnk)
+                                               (link-name lnk)))))
                  (define exports+locals (bootstrap:s-expr-linklet-exports+locals (linklet-info-linklet li)))
                  (for/or ([export+local (in-list exports+locals)])
                    (and (eq? external (car export+local))
diff --git a/racket/src/expander/run.rkt b/racket/src/expander/run.rkt
index 13f6bc837d..4c6671bbdd 100644
--- a/racket/src/expander/run.rkt
+++ b/racket/src/expander/run.rkt
@@ -108,19 +108,20 @@
    [("-B") "Print extracted bootstrap as bytecode"
     (set! extract-to-bytecode? #t)]
    #:multi
-   [("++knot") sym path "Redirect imports from <sym> to flattened from <path>"
+   [("++knot") primitive-table path ("Redirect imports from #%<primitive-table> to flattened from <path>;"
+                                     " use `-` for <path> to leave as-is, effectively redirecting to a primitive use")
     (hash-update! instance-knot-ties
-                  (string->symbol (format "#%~a" sym))
+                  (string->symbol (format "#%~a" primitive-table))
                   (lambda (l) (cons (if (equal? path "-")
 					'ignore
 					(path->complete-path (normal-case-path path)))
 				    l))
                   null)]
-   [("++direct") primitive-table "Redirect imports from #%<primitive-table> to direct references"
+   [("++direct") primitive-table "Redirect from `(primitive-table '#%<primitive-table>)` to primitive use"
     (hash-set! primitive-table-directs
                (string->symbol (string-append "#%" primitive-table))
                "")]
-   [("++direct-prefixed") primitive-table "Like ++direct, but prefixes with <primitive-table>:"
+   [("++direct-prefixed") primitive-table "Like ++direct, but prefix with <primitive-table>:"
     (hash-set! primitive-table-directs
                (string->symbol (string-append "#%" primitive-table))
                (string-append primitive-table ":"))]