diff --git a/honoka/plugins/primeprediction.cpp b/honoka/plugins/primeprediction.cpp
index 038eea6..6fcdc42 100644
--- a/honoka/plugins/primeprediction.cpp
+++ b/honoka/plugins/primeprediction.cpp
@@ -37,6 +37,10 @@
   #define bind_textdomain_codeset(domain,codeset)
 #endif
 
+#include <sys/types.h>
+#include <sys/wait.h>
+
+
 // �ץ饤�����󲽤Τ��ޤ��ʤ��Ǥ���
 HonokaPluginRegister(PrimePrediction);
 
@@ -100,6 +104,8 @@
  */
 ResultList PrimePrediction::getPredictionList(const WideString &str)
 {
+    ResultList l;
+    if (!con) return l;
     String s = lookup_method + "\t";
     String t;
     m_iconv.convert(t,str);
@@ -121,26 +127,9 @@
         } else t += s[i];
     }
     if (t.length()) sl.push_back(t);
-    ResultList l;
     l.Title = utf8_mbstowcs(String(_("lookup result")));
     l.kType = PREDICTION;
     for(unsigned int i = 1;i < sl.size();i ++) {
-        /*vector<String> rl;
-        String r;
-        for(unsigned int j = 0;j < sl[i].length();j ++) {
-            if ((sl[i][j] == '\t') || (sl[i][j] == ' ')) {
-                if (r.length()) {
-                    rl.push_back(r);
-                    r = "";
-                }
-            } else r += sl[i][j];
-        }
-        if (r.length()) rl.push_back(r);
-        if (rl.size() < 2) continue;
-        WideString w;
-        m_iconv.convert(w,rl[1]);
-        l.kouho.push_back(ResultEntry(w));
-        */
         ResultEntry e = parser(sl[i]);
         if (e.kanji.length()) l.kouho.push_back(e);
     }
@@ -153,10 +142,12 @@
  */
 void PrimePrediction::disconnect()
 {
+    if (!con) return;
     String s = "close\n";
     write(ifd,s.c_str(),s.length());
     close(ifd);
     close(ofd);
+    con = false;
 }
 
 
@@ -169,8 +160,7 @@
     if (con) return true;
     if (pipe(in_fd) == -1) return false;
     if (pipe(out_fd) == -1) return false;
-    con = true;
-    switch(fork()) {
+    switch(vfork()) {
         case -1: {
             close(in_fd[0]);
             close(in_fd[1]);
@@ -186,9 +176,10 @@
             dup2(out_fd[1],1);
             close(in_fd[0]);
             close(out_fd[1]);
+            con = true;
             execlp("prime",NULL);
             con = false;
-            exit(1);
+            _exit(0);
         }
     }
     close(in_fd[0]);