diff --git a/collects/drracket/private/syncheck/traversals.rkt b/collects/drracket/private/syncheck/traversals.rkt
index 0ab439db10..e156fd40da 100644
--- a/collects/drracket/private/syncheck/traversals.rkt
+++ b/collects/drracket/private/syncheck/traversals.rkt
@@ -1228,14 +1228,15 @@
                  (when ed
                    (define pos (syntax-position var))
                    (define span (syntax-span var))
-                   (define start (- pos 1))
-                   (define fin (+ start span))
-                   (define loc (list ed start fin))
-                   (module-identifier-mapping-put!
-                    id-to-sets
-                    var
-                    (set-add (module-identifier-mapping-get id-to-sets var set)
-                             loc)))))))
+                   (when (and pos span)
+                     (define start (- pos 1))
+                     (define fin (+ start span))
+                     (define loc (list ed start fin))
+                     (module-identifier-mapping-put!
+                      id-to-sets
+                      var
+                      (set-add (module-identifier-mapping-get id-to-sets var set)
+                               loc))))))))
           (module-identifier-mapping-for-each
            id-to-sets
            (λ (id locs)
diff --git a/collects/tests/drracket/syncheck-direct.rkt b/collects/tests/drracket/syncheck-direct.rkt
index 6e7ab1a672..7b272de3e3 100644
--- a/collects/tests/drracket/syncheck-direct.rkt
+++ b/collects/tests/drracket/syncheck-direct.rkt
@@ -66,3 +66,24 @@
                                (let ([y 1]) y)))))))
      (done))
    add-arrow-called?))
+
+(check-not-exn
+ (λ ()
+   (define annotations
+     (new (class (annotations-mixin object%)
+            (super-new)
+            (define/override (syncheck:find-source-object stx)
+              stx))))
+   
+   (define base-namespace (make-base-namespace))
+   (define-values (add-syntax done)
+     (make-traversal base-namespace #f))
+   
+   (parameterize ([current-annotations annotations]
+                  [current-namespace base-namespace])
+     (eval '(require (for-syntax racket/base)))
+     (add-syntax
+      (expand
+       '(let-syntax ([m (λ (_) #`(let ([x 1]) x))])
+          (m))))
+     (done))))
\ No newline at end of file