diff --git a/src/dialog/vfileinfodialog.cpp b/src/dialog/vfileinfodialog.cpp
index b7087770..51ffe3b0 100644
--- a/src/dialog/vfileinfodialog.cpp
+++ b/src/dialog/vfileinfodialog.cpp
@@ -3,6 +3,7 @@
 #include "vdirectory.h"
 #include "vfile.h"
 #include "vconfigmanager.h"
+#include "utils/vutils.h"
 
 extern VConfigManager *g_config;
 
@@ -74,6 +75,14 @@ void VFileInfoDialog::handleInputChanged()
                                           "Please choose another name.")
                                           .arg(g_config->c_warningTextStyle);
             m_warnLabel->setText(nameConflictText);
+        } else if (VUtils::docTypeFromName(name) != m_file->getDocType()) {
+            // Check if the name change the doc type.
+            nameOk = false;
+            showWarnLabel = true;
+            QString nameConflictText = tr("<span style=\"%1\">WARNING</span>: Changing type of the note is not supported. "
+                                          "Please use the same suffix as the old one.")
+                                          .arg(g_config->c_warningTextStyle);
+            m_warnLabel->setText(nameConflictText);
         }
     }
 
diff --git a/src/vdirectory.cpp b/src/vdirectory.cpp
index 378f3e80..d9d05015 100644
--- a/src/vdirectory.cpp
+++ b/src/vdirectory.cpp
@@ -528,9 +528,7 @@ VFile *VDirectory::copyFile(VDirectory *p_destDir, const QString &p_destName,
         return NULL;
     }
 
-    if (docType != newDocType) {
-        destFile->convert(docType, newDocType);
-    }
+    Q_ASSERT(docType == newDocType);
 
     // We need to copy internal images when it is still markdown.
     if (!images.isEmpty()) {
diff --git a/src/vfile.cpp b/src/vfile.cpp
index d30c0c81..f22106e5 100644
--- a/src/vfile.cpp
+++ b/src/vfile.cpp
@@ -69,27 +69,6 @@ bool VFile::save()
     return ret;
 }
 
-void VFile::convert(DocType p_curType, DocType p_targetType)
-{
-    Q_ASSERT(!m_opened);
-    m_docType = p_targetType;
-    if (p_curType == p_targetType) {
-        return;
-    }
-    QString path = fetchPath();
-    QString fileText = VUtils::readFileFromDisk(path);
-    QTextEdit editor;
-    if (p_curType == DocType::Markdown) {
-        editor.setPlainText(fileText);
-        fileText = editor.toHtml();
-    } else {
-        editor.setHtml(fileText);
-        fileText = editor.toPlainText();
-    }
-    VUtils::writeFileToDisk(path, fileText);
-    qDebug() << getName() << "converted" << (int)p_curType << (int)p_targetType;
-}
-
 void VFile::setModified(bool p_modified)
 {
     m_modified = p_modified;
@@ -264,12 +243,8 @@ bool VFile::rename(const QString &p_name)
         return false;
     }
 
-    // Handle DocType change.
-    DocType newType = VUtils::docTypeFromName(m_name);
-    if (m_docType != newType) {
-        convert(m_docType, newType);
-        m_docType = newType;
-    }
+    // Can't not change doc type.
+    Q_ASSERT(m_docType == VUtils::docTypeFromName(m_name));
 
     qDebug() << "note renamed from" << oldName << "to" << m_name;
 
diff --git a/src/vfile.h b/src/vfile.h
index 3186be97..d1717e03 100644
--- a/src/vfile.h
+++ b/src/vfile.h
@@ -19,8 +19,6 @@ public:
     virtual bool open();
     virtual void close();
     virtual bool save();
-    // Convert current file type.
-    virtual void convert(DocType p_curType, DocType p_targetType);
 
     const QString &getName() const;
     virtual void setName(const QString &p_name);
diff --git a/src/vfilelist.cpp b/src/vfilelist.cpp
index 78ef715e..615b56a0 100644
--- a/src/vfilelist.cpp
+++ b/src/vfilelist.cpp
@@ -198,9 +198,7 @@ void VFileList::fileInfo(VFile *p_file)
             return;
         }
 
-        if (!promptForDocTypeChange(p_file, QDir(p_file->fetchBasePath()).filePath(name))) {
-            return;
-        }
+        Q_ASSERT(p_file->getDocType() == VUtils::docTypeFromName(name));
 
         if (!p_file->rename(name)) {
             VUtils::showMessage(QMessageBox::Warning, tr("Warning"),
@@ -579,10 +577,8 @@ bool VFileList::copyFile(VDirectory *p_destDir, const QString &p_destName, VFile
         return true;
     }
 
-    // If change the file type, we need to close it first
-    if (!promptForDocTypeChange(p_file, destPath)) {
-        return false;
-    }
+    // DocType is not allowed to change.
+    Q_ASSERT(p_file->getDocType() == VUtils::docTypeFromName(destPath));
 
     VFile *destFile = VDirectory::copyFile(p_destDir, p_destName, p_file, p_cut);
     updateFileList();
@@ -592,31 +588,6 @@ bool VFileList::copyFile(VDirectory *p_destDir, const QString &p_destName, VFile
     return destFile != NULL;
 }
 
-bool VFileList::promptForDocTypeChange(const VFile *p_file, const QString &p_newFilePath)
-{
-    DocType docType = p_file->getDocType();
-    DocType newDocType = VUtils::docTypeFromName(p_newFilePath);
-
-    if (docType != newDocType) {
-        if (editArea->isFileOpened(p_file)) {
-            int ret = VUtils::showMessage(QMessageBox::Warning, tr("Warning"),
-                                          tr("The renaming will change the note type."),
-                                          tr("You should close the note <span style=\"%1\">%2</span> before continue.")
-                                            .arg(g_config->c_dataTextStyle).arg(p_file->getName()),
-                                          QMessageBox::Ok | QMessageBox::Cancel, QMessageBox::Ok, this);
-            if (QMessageBox::Ok == ret) {
-                if (!editArea->closeFile(p_file, false)) {
-                    return false;
-                }
-            } else {
-                return false;
-            }
-        }
-    }
-
-    return true;
-}
-
 void VFileList::keyPressEvent(QKeyEvent *event)
 {
     int key = event->key();
diff --git a/src/vfilelist.h b/src/vfilelist.h
index 04727821..6460176d 100644
--- a/src/vfilelist.h
+++ b/src/vfilelist.h
@@ -91,13 +91,6 @@ private:
     bool identicalListWithDirectory() const;
     QList<QListWidgetItem *> getVisibleItems() const;
 
-    // @p_file: the file to be renamed or copied.
-    // @p_newFilePath: the new file path of @p_file.
-    // Check if the rename/copy will change the DocType. If yes, then ask
-    // user for confirmation.
-    // Return true if we can continue.
-    bool promptForDocTypeChange(const VFile *p_file, const QString &p_newFilePath);
-
     // Fill the info of @p_item according to @p_file.
     void fillItem(QListWidgetItem *p_item, const VFile *p_file);
 
diff --git a/src/vorphanfile.cpp b/src/vorphanfile.cpp
index 33d10748..0d864091 100644
--- a/src/vorphanfile.cpp
+++ b/src/vorphanfile.cpp
@@ -69,11 +69,6 @@ bool VOrphanFile::save()
     return VUtils::writeFileToDisk(fetchPath(), m_content);
 }
 
-void VOrphanFile::convert(DocType /* p_curType */, DocType /* p_targetType */)
-{
-    V_ASSERT(false);
-}
-
 void VOrphanFile::setName(const QString & /* p_name */)
 {
     V_ASSERT(false);
diff --git a/src/vorphanfile.h b/src/vorphanfile.h
index 7f3e8b7f..4deb3a8e 100644
--- a/src/vorphanfile.h
+++ b/src/vorphanfile.h
@@ -40,7 +40,6 @@ public:
 
 private:
     bool save() Q_DECL_OVERRIDE;
-    void convert(DocType p_curType, DocType p_targetType) Q_DECL_OVERRIDE;
     void setName(const QString &p_name) Q_DECL_OVERRIDE;
     QString fetchImagePath() const Q_DECL_OVERRIDE;
     void setContent(const QString &p_content) Q_DECL_OVERRIDE;