diff --git a/src/backends/maxima/maximasyntaxhelpobject.cpp b/src/backends/maxima/maximasyntaxhelpobject.cpp
index f4f29866..f9b6c831 100644
--- a/src/backends/maxima/maximasyntaxhelpobject.cpp
+++ b/src/backends/maxima/maximasyntaxhelpobject.cpp
@@ -1,120 +1,118 @@
 /*
     This program is free software; you can redistribute it and/or
     modify it under the terms of the GNU General Public License
     as published by the Free Software Foundation; either version 2
     of the License, or (at your option) any later version.
 
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 
     You should have received a copy of the GNU General Public License
     along with this program; if not, write to the Free Software
     Foundation, Inc., 51 Franklin Street, Fifth Floor,
     Boston, MA  02110-1301, USA.
 
     ---
     Copyright (C) 2009-2012 Alexander Rieder <alexanderrieder@gmail.com>
  */
 
 #include "maximasyntaxhelpobject.h"
 #include "maximakeywords.h"
 
 #include "maximasession.h"
 #include "maximaexpression.h"
 
 #include "result.h"
 
 #include <QDebug>
 
 MaximaSyntaxHelpObject::MaximaSyntaxHelpObject(const QString& cmd, MaximaSession* session) : Cantor::SyntaxHelpObject(cmd, session)
 {
     m_expression=nullptr;
 }
 
 void MaximaSyntaxHelpObject::fetchInformation()
 {
-    if(m_expression)
-    {
-        m_expression->setFinishingBehavior(Cantor::Expression::DeleteOnFinish);
-    }
-
     bool isValid=false;
     for (const QString& func : MaximaKeywords::instance()->functions())
     {
         if(command()==func)
         {
             isValid=true;
             break;
         }
     }
 
     if(isValid)
     {
         if (session()->status() != Cantor::Session::Disable)
         {
+            if (m_expression)
+                return;
+
             //use the lisp command, instead of directly calling the
             //maxima function "describe" to avoid generating a new
             //output label that would mess up history
             QString cmd=QLatin1String(":lisp(cl-info::info-exact \"%1\")");
 
             m_expression=session()->evaluateExpression(cmd.arg(command()), Cantor::Expression::FinishingBehavior::DoNotDelete, true);
 
             connect(m_expression, &Cantor::Expression::statusChanged, this, &MaximaSyntaxHelpObject::expressionChangedStatus);
         }
         else
             // We can't get function's detailed description, because session not login yet, so do nothing
             emit done();
 
     }else
     {
         qDebug()<<"invalid syntax request";
         emit done();
     }
 }
 
 void MaximaSyntaxHelpObject::expressionChangedStatus(Cantor::Expression::Status status)
 {
     switch(status)
     {
         case Cantor::Expression::Done:
         {
             qDebug()<<"expr done";
             QString text=m_expression->result()->toHtml();
             QStringList lines=text.split(QLatin1Char('\n'));
 
             QString syntax;
             for (QString line : lines)
             {
                 if(line.endsWith(QLatin1Char('\r')))
                     line.chop(1);
                 if(line.startsWith(QLatin1String("-- Function:")))
                 {
                     line.remove(QLatin1String("-- Function:"));
                     line.remove(QLatin1String("<br/>"));
                 }
                 syntax+=line;
                 qDebug() << "line: " << line;
             }
 
             setHtml(QLatin1String("<p style='white-space:pre'>")+syntax+QLatin1String("</p>"));
             emit done();
 
             m_expression->deleteLater();
             m_expression=nullptr;
             break;
         }
         case Cantor::Expression::Error:
         {
             qWarning() << "syntax object error" << m_expression->result()->toHtml();
             emit done();
 
             m_expression->deleteLater();
             m_expression=nullptr;
             break;
         }
         default:
             break;
     }
 }