diff --git a/collects/plai/mutator.rkt b/collects/plai/mutator.rkt
index 6d34d1bebc..4c2dfefd10 100644
--- a/collects/plai/mutator.rkt
+++ b/collects/plai/mutator.rkt
@@ -110,7 +110,7 @@
     [(_) (mutator-app void)]
     [(_ e) e]
     [(_ fe e ...)
-     (mutator-let ([tmp fe]) (mutator-begin e ...))]))
+     (let ([tmp fe]) (mutator-begin e ...))]))
 
 ; Real Macros
 (define-syntax-rule (mutator-define-values (id ...) e)
diff --git a/collects/tests/plai/gc/good-mutators/thunks.rkt b/collects/tests/plai/gc/good-mutators/thunks.rkt
new file mode 100755
index 0000000000..4191318180
--- /dev/null
+++ b/collects/tests/plai/gc/good-mutators/thunks.rkt
@@ -0,0 +1,15 @@
+#lang plai/mutator
+(allocator-setup "../good-collectors/good-collector.ss" 4)
+
+; 2
+(define thunker
+  (lambda ()
+    ; 2
+    'alligator
+    ; 2
+    'bananna
+    ; 2
+    'frog))
+; 4 total
+
+(thunker)
\ No newline at end of file