diff --git a/host/chez/build.ss b/host/chez/build.ss
index ca57ed1..f2d68fc 100644
--- a/host/chez/build.ss
+++ b/host/chez/build.ss
@@ -184,10 +184,15 @@
                        (bfs (append (or (hashtable-ref edges fq #f) '()) (cdr work))))))))
       (let ((kept? (lambda (r) (or (vector-ref r 0) (hashtable-ref reached (vector-ref r 1) #f))))
             (refs-any (lambda (r set) (ormap (lambda (b) (and (member b (vector-ref r 2)) #t)) set)))
-            (bail #f) (needs-compiler #f))
+            (bail #f) (bail-why '()) (needs-compiler #f))
         (for-each (lambda (r)
                     (when (kept? r)
-                      (when (refs-any r dce-bail-refs) (set! bail #t))
+                      (for-each (lambda (b)
+                                  (when (member b (vector-ref r 2))
+                                    (set! bail #t)
+                                    (when (< (length bail-why) 6)
+                                      (set! bail-why (cons (cons (or (vector-ref r 1) "<form>") b) bail-why)))))
+                                dce-bail-refs)
                       (when (refs-any r dce-compile-refs) (set! needs-compiler #t))))
                   all)
         (let ((drop-compiler? (and (not bail) (not needs-compiler)))
@@ -202,7 +207,9 @@
                                         (if isdef (+ n 1) n) (if isdef (+ k 1) k))
                                   (loop (cdr rs) acc (if isdef (+ n 1) n) k))))))))
           (if bail
-              (begin (display "jolt build: tree-shake skipped (reachable code resolves vars at runtime)\n")
+              (begin (display "jolt build: tree-shake skipped (reachable code resolves vars at runtime):\n")
+                     (for-each (lambda (w) (display (string-append "  " (car w) " -> " (cdr w) "\n")))
+                               (reverse bail-why))
                      (values #f (map (lambda (r) (vector-ref r 3)) app-records) drop-compiler?))
               (let-values (((core-strs cn ck) (pick core-records))
                            ((app-strs an ak) (pick app-records)))