diff --git a/pkgs/racket-test-core/tests/racket/struct.rktl b/pkgs/racket-test-core/tests/racket/struct.rktl
index 31f87d768d..ffbdf1f1c1 100644
--- a/pkgs/racket-test-core/tests/racket/struct.rktl
+++ b/pkgs/racket-test-core/tests/racket/struct.rktl
@@ -647,6 +647,11 @@
 (test #f inspector-superior? (make-inspector) (make-inspector))
 (test #t inspector-superior? (current-inspector) (make-inspector (make-inspector (make-inspector))))
 
+(test #t inspector? (make-sibling-inspector))
+(test #f inspector-superior? (current-inspector) (make-sibling-inspector))
+(test #f inspector-superior? (make-sibling-inspector) (current-inspector))
+(test #t inspector-superior? (current-inspector) (make-sibling-inspector (make-inspector)))
+
 ;; ------------------------------------------------------------
 ;; Property accessor errors
 
diff --git a/racket/src/cs/rumble/struct.ss b/racket/src/cs/rumble/struct.ss
index eec053f35b..6069ec0f8c 100644
--- a/racket/src/cs/rumble/struct.ss
+++ b/racket/src/cs/rumble/struct.ss
@@ -133,10 +133,10 @@
 
 (define/who make-sibling-inspector
   (case-lambda
-   [() (make-sibling-inspector (current-inspector))]
+   [() (make-sibling-inspector (|#%app| current-inspector))]
    [(i)
     (check who inspector? i)
-    (make-inspector (inspector-parent i))]))
+    (new-inspector (inspector-parent i))]))
 
 (define/who (inspector-superior? sup-insp sub-insp)
   (check who inspector? sup-insp)
@@ -145,7 +145,8 @@
       #f
       (let ([parent (inspector-parent sub-insp)])
         (or (eq? parent sup-insp)
-            (inspector-superior? sup-insp parent)))))
+            (and parent
+                 (inspector-superior? sup-insp parent))))))
 
 (define (inspector-ref rtd)
   (getprop (record-type-uid rtd) 'inspector none))