diff --git a/fsencoding.cc b/fsencoding.cc
index 822a08cc..64aef4ec 100644
--- a/fsencoding.cc
+++ b/fsencoding.cc
@@ -21,7 +21,7 @@ string encode( wstring const & str )
 string encode( string const & str )
 {
 #ifdef __WIN32
-  return str;
+  return string( str );
 #else
   return string( QString::fromUtf8( str.c_str() ).toLocal8Bit().data() );
 #endif
diff --git a/wstring_qt.cc b/wstring_qt.cc
index 94febc69..aa9d9f6a 100644
--- a/wstring_qt.cc
+++ b/wstring_qt.cc
@@ -10,7 +10,17 @@ namespace gd
 
   wstring toWString( QString const & in )
   {
-    return in.toStdU32String();
+    QVector< unsigned int > v = in.toUcs4();
+
+    // Fix for QString instance which contains non-BMP characters
+    // Qt will created unexpected null characters may confuse btree indexer.
+    // Related: https://bugreports.qt-project.org/browse/QTBUG-25536
+    int n = v.size();
+    while ( n > 0 && v[ n - 1 ] == 0 ) n--;
+    if ( n != v.size() )
+      v.resize( n );
+
+    return wstring( ( const wchar * ) v.constData(), v.size() );
   }
 
   wstring normalize( const wstring & str )