diff --git a/collects/plai/gc2/mutator.rkt b/collects/plai/gc2/mutator.rkt
index dc6b0b5f1f..efae8f0c58 100644
--- a/collects/plai/gc2/mutator.rkt
+++ b/collects/plai/gc2/mutator.rkt
@@ -206,7 +206,11 @@
   (syntax-case stx ()
     [(_ (id ...) body)
      (let ([env-roots (syntax-parameter-value #'mutator-env-roots)])
-       (with-syntax ([(free-id ...) (map syntax-local-introduce (find-referenced-locals env-roots stx))]
+       (with-syntax ([(free-id ...) (map syntax-local-introduce 
+                                         (filter
+                                          (λ (x) (for/and ([id (in-list (syntax->list #'(id ...)))])
+                                                   (not (free-identifier=? id x))))
+                                          (find-referenced-locals env-roots stx)))]
                      [(env-id ...) env-roots]
                      [closure (or (syntax-parameter-value #'mutator-name)
                                   (syntax-local-name)
diff --git a/collects/tests/plai/gc2/good-mutators/nested-lam.rkt b/collects/tests/plai/gc2/good-mutators/nested-lam.rkt
new file mode 100644
index 0000000000..9c167c0ced
--- /dev/null
+++ b/collects/tests/plai/gc2/good-mutators/nested-lam.rkt
@@ -0,0 +1,6 @@
+#lang plai/gc2/mutator
+(allocator-setup "../good-collectors/good-collector.rkt" 40)
+(let ([x 1])
+  ((λ (x)
+     x)
+   x))