diff --git a/src/frontends/qt/qt_helpers.cpp b/src/frontends/qt/qt_helpers.cpp
index db39b4c5f0..0431c042ad 100644
--- a/src/frontends/qt/qt_helpers.cpp
+++ b/src/frontends/qt/qt_helpers.cpp
@@ -214,22 +214,6 @@ QString formatLocFPNumber(double d)
 }
 
 
-QString locLengthString(QString const & str)
-{
-	QLocale loc;
-	QString res = str;
-	return res.replace(QString("."), loc.decimalPoint());
-}
-
-
-QString unlocLengthString(QString const & str)
-{
-	QLocale loc;
-	QString res = str;
-	return res.replace(loc.decimalPoint(), QString("."));
-}
-
-
 bool SortLocaleAware(QString const & lhs, QString const & rhs)
 {
 	return QString::localeAwareCompare(lhs, rhs) < 0;
diff --git a/src/frontends/qt/qt_helpers.h b/src/frontends/qt/qt_helpers.h
index 07812c3d92..08d50fa582 100644
--- a/src/frontends/qt/qt_helpers.h
+++ b/src/frontends/qt/qt_helpers.h
@@ -72,12 +72,6 @@ void doubleToWidget(QLineEdit * input, std::string const & value,
  */
 QString formatLocFPNumber(double d);
 
-/// Method to replace dot with localized decimal separator
-QString locLengthString(QString const & str);
-
-/// Method to replace localized decimal separator by dot
-QString unlocLengthString(QString const & str);
-
 /// Method to sort QStrings locale-aware (e.g. in combo widgets)
 bool SortLocaleAware(QString const & lhs, QString const & rhs);
 
diff --git a/src/support/qstring_helpers.cpp b/src/support/qstring_helpers.cpp
index bb800f3c67..fadca76a65 100644
--- a/src/support/qstring_helpers.cpp
+++ b/src/support/qstring_helpers.cpp
@@ -19,6 +19,7 @@
 #include "support/qstring_helpers.h"
 
 #include <QRegExp>
+#include <QLocale>
 #include <QString>
 #include <QVector>
 
@@ -101,6 +102,26 @@ QString charFilterRegExpC(QString const & filter)
 	return re + ")";
 }
 
+QString locLengthString(QString const & str)
+{
+	QLocale loc;
+	QString res = str;
+	return res.replace(QString("."), loc.decimalPoint());
+}
+
+
+docstring locLengthDocString(docstring const str)
+{
+	return qstring_to_ucs4(locLengthString(toqstr(str)));
+}
+
+
+QString unlocLengthString(QString const & str)
+{
+	QLocale loc;
+	QString res = str;
+	return res.replace(loc.decimalPoint(), QString("."));
+}
 
 
 } // namespace lyx
diff --git a/src/support/qstring_helpers.h b/src/support/qstring_helpers.h
index e33131caa5..905343e77d 100644
--- a/src/support/qstring_helpers.h
+++ b/src/support/qstring_helpers.h
@@ -92,6 +92,15 @@ QString charFilterRegExp(QString const & filter);
  */
 QString charFilterRegExpC(QString const & filter);
 
+/// Method to replace dot with localized decimal separator
+QString locLengthString(QString const & str);
+
+/// Same for doscstring
+docstring locLengthDocString(docstring const str);
+
+/// Method to replace localized decimal separator by dot
+QString unlocLengthString(QString const & str);
+
 } // namespace lyx
 
 #endif // QSTRING_HELPERS_H