diff --git a/dictionary.cc b/dictionary.cc
index a00de8e3..c028c214 100644
--- a/dictionary.cc
+++ b/dictionary.cc
@@ -579,14 +579,63 @@ bool needToRebuildIndex( vector< string > const & dictionaryFiles,
 
   return fileInfo.lastModified().toSecsSinceEpoch() < lastModified;
 #else
-  QDir d(FsEncoding::decode( indexFile.c_str() ));
-  if(!d.exists()){
+  QFileInfo fileInfo( FsEncoding::decode( indexFile.c_str() ) );
+
+  if ( fileInfo.exists()&&fileInfo.isFile() )
+  {
+    QFile::remove(FsEncoding::decode( indexFile.c_str() ));
     return true;
   }
+
   return false;
 #endif
 }
 
+bool needToRebuildBTreeIndex( vector< string > const & dictionaryFiles,
+                         string const & indexFile ) noexcept
+{
+  unsigned long lastModified = 0;
+
+  for( std::vector< string >::const_iterator i = dictionaryFiles.begin();
+       i != dictionaryFiles.end(); ++i )
+  {
+    QString name = FsEncoding::decode( i->c_str() );
+    QFileInfo fileInfo( name );
+    unsigned long ts;
+
+    if( fileInfo.isDir() )
+      continue;
+
+    if( name.toLower().endsWith( ".zip" ) )
+    {
+      ZipFile::SplitZipFile zf( name );
+      if( !zf.exists() )
+        return true;
+      ts = zf.lastModified().toSecsSinceEpoch();
+    }
+    else
+    {
+      if ( !fileInfo.exists() )
+        return true;
+      ts = fileInfo.lastModified().toSecsSinceEpoch();
+    }
+
+    if ( ts > lastModified )
+      lastModified = ts;
+  }
+
+  QDir d(FsEncoding::decode( indexFile.c_str() ));
+  if(d.exists()){
+    d.removeRecursively();
+  }
+  QFileInfo fileInfo( FsEncoding::decode( indexFile.c_str() ) );
+
+  if ( !fileInfo.exists() )
+    return true;
+
+  return fileInfo.lastModified().toSecsSinceEpoch() < lastModified;
+}
+
 QString generateRandomDictionaryId()
 {
   return QString(
diff --git a/dictionary.hh b/dictionary.hh
index 369f8300..493f158b 100644
--- a/dictionary.hh
+++ b/dictionary.hh
@@ -483,6 +483,9 @@ string makeDictionaryId( vector< string > const & dictionaryFiles ) noexcept;
 bool needToRebuildIndex( vector< string > const & dictionaryFiles,
                          string const & indexFile ) noexcept;
 
+bool needToRebuildBTreeIndex( vector< string > const & dictionaryFiles,
+                         string const & indexFile ) noexcept;
+
 /// Returns a random dictionary id useful for interactively created
 /// dictionaries.
 QString generateRandomDictionaryId();
diff --git a/mdx.cc b/mdx.cc
index efe3d4dc..2c135c12 100644
--- a/mdx.cc
+++ b/mdx.cc
@@ -1401,7 +1401,7 @@ vector< sptr< Dictionary::Class > > makeDictionaries( vector< string > const & f
     string dictId = Dictionary::makeDictionaryId( dictFiles );
     string indexFile = indicesDir + dictId;
 
-    if ( Dictionary::needToRebuildIndex( dictFiles, indexFile ) ||
+    if ( Dictionary::needToRebuildBTreeIndex( dictFiles, indexFile ) ||
          indexIsOldOrBad( dictFiles, indexFile ) )
     {
       // Building the index