diff --git a/collects/mzlib/cm-accomplice.ss b/collects/mzlib/cm-accomplice.ss
index 2cd62c6..d9ceaa9 100644
--- a/collects/mzlib/cm-accomplice.ss
+++ b/collects/mzlib/cm-accomplice.ss
@@ -5,8 +5,12 @@
     (unless (and (string? f)
 		 (complete-path? f))
       (raise-type-error 'register-external-file "complete-path string" f))
-    (let ([param (dynamic-require-for-syntax '(lib "cm-ctime.ss" "mzlib" "private")
-					     'current-external-file-registrar)])
+    (let ([param (lambda () void)])
+      (thread-wait 
+       (thread (lambda ()
+		 (set! param
+		       (dynamic-require '(lib "cm-ctime.ss" "mzlib" "private")
+					'current-external-file-registrar)))))
       ((param) f))))