diff --git a/graph-lib/make/make-lib-2.rkt b/graph-lib/make/make-lib-2.rkt
index 35484e50..7bbea1fc 100644
--- a/graph-lib/make/make-lib-2.rkt
+++ b/graph-lib/make/make-lib-2.rkt
@@ -1,5 +1,8 @@
 #lang racket
 
+;; TODO: use (or (file-exists? path) (directory-exists? path)
+;; (link-exists? path)), when checking whether the output was created.
+
 (require (for-syntax syntax/parse)
          rackunit)
 
@@ -41,4 +44,4 @@
 
 (check-equal? (match (build-path "a/b/c/d/e/f" 'up "g/")
                 ((simple-path x y ... z) (simple-path z y ... 'up x)))
-              (string->path "g/b/c/d/a"))
\ No newline at end of file
+              (string->path "g/b/c/d/a"))
diff --git a/graph-lib/make/make.rkt b/graph-lib/make/make.rkt
index b5d8f509..a91b4b97 100644
--- a/graph-lib/make/make.rkt
+++ b/graph-lib/make/make.rkt
@@ -143,8 +143,9 @@
 ;; Create root MathJax link, must be done before the others
 ;; Otherwise make/proc thinks the (broken) link hasn't been created.
 (make-directory* "docs/") ;; docs/ must be created before Depencency graph too
-(make-file-or-directory-link (build-path 'up "lib" "doc" "MathJax")
-                             (build-path "docs" "MathJax"))
+(unless (link-exists? (build-path "docs" "MathJax"))
+  (make-file-or-directory-link (build-path 'up "lib" "doc" "MathJax")
+                               (build-path "docs" "MathJax")))
 
 
 ;; Dependency graph, must be done before docs.