diff --git a/honoka/plugins/wnnconversion.cpp b/honoka/plugins/wnnconversion.cpp
index b70022a..9460288 100644
--- a/honoka/plugins/wnnconversion.cpp
+++ b/honoka/plugins/wnnconversion.cpp
@@ -216,6 +216,7 @@
  */
 int WnnConversion::ren_conversion()
 {
+    if ((yomiText.length() > 500) || (!yomiText.length())) return -1;
     convList.Yomi.clear();
     convList.kouho.clear();
     bunList.clear();
diff --git a/honoka/src/honoka_imengine.cpp b/honoka/src/honoka_imengine.cpp
index e9c3177..24efa04 100644
--- a/honoka/src/honoka_imengine.cpp
+++ b/honoka/src/honoka_imengine.cpp
@@ -1257,7 +1257,7 @@
 
     m_convertor->setYomiText(s);
     if (m_convertor->ren_conversion() == -1) {
-        update_aux_string(utf8_mbstowcs(String(_("could not connect to server."))));
+        update_aux_string(utf8_mbstowcs(String(_("The error was received from Converter. "))));
         show_aux_string();
         m_convertor = m_def_convertor;
         return;