diff --git a/core/src/magic.sld b/core/src/magic.sld
index 1453903..54b103b 100644
--- a/core/src/magic.sld
+++ b/core/src/magic.sld
@@ -554,7 +554,7 @@
         (cons
          (thread-start!
            (make-thread
-            (lambda () (call/cc (lambda (cc) (builder cc (daemon-connect)))))
+            (lambda () (define thread-conn (daemon-connect)) (call/cc (lambda (cc) (builder cc thread-conn))) (daemon-close thread-conn))
             (string-append "ca-builder-" (number->string i))))
          builder-threads)))