diff --git a/doerg/src/net/deertopia/doerg/tex/temml.clj b/doerg/src/net/deertopia/doerg/tex/temml.clj
index 22082fb..fed2aff 100644
--- a/doerg/src/net/deertopia/doerg/tex/temml.clj
+++ b/doerg/src/net/deertopia/doerg/tex/temml.clj
@@ -17,13 +17,17 @@
 
 (def ^:dynamic *worker*)
 
-(def ^:private prelude-file
-  (fs/create-temp-file {:prefix "doerg-prelude-"
-                        :suffix ".tex"}))
+;; 외부의 브로그램이 JVM resource를 사용 위해서 파일 시스템에서 써야
+;; 합니다.
+(defonce ^:private prelude-file
+  (-> (fs/create-temp-file {:prefix "doerg-prelude-"
+                            :suffix ".tex"})
+      fs/file))
 
 (defn worker []
   (let [doerg-temml-worker (-> cfg/*cfg* ::doerg/doerg-temml-worker)]
-    (when-not (fs/exists? prelude-file)
+    (when (or (not (fs/exists? prelude-file))
+              (zero? (fs/size prelude-file)))
       (-> "net/deertopia/doerg/prelude.tex"
           io/resource
           io/input-stream
@@ -55,7 +59,11 @@
 (defn command-worker [x]
   (cbor/encode cbor/default-codec (:in *worker*) x)
   (.flush (:in *worker*))
-  (cbor/decode cbor/default-codec (:out *worker*)))
+  (let [r (cbor/decode cbor/default-codec (:out *worker*))]
+    (if (string? r)
+      r
+      (throw (ex-info "bad data from temml worker"
+                      {:data r})))))
 
 (defn render-inline [s]
   (command-worker s))