diff -r 1f15c52c11f6 -r 4c7a353cf583 src/editmodes/abstractEditMode.cpp
--- a/src/editmodes/abstractEditMode.cpp	Sat Jan 28 14:01:19 2017 +0200
+++ b/src/editmodes/abstractEditMode.cpp	Sat Jan 28 14:13:01 2017 +0200
@@ -190,7 +190,7 @@
 	if (not m_config->drawLineLengths())
 		return;
 
-	const QString label = QString::number ((v1 - v0).length(), 'f', 2);
+	const QString label = QString::number(abs(v1 - v0), 'f', 2);
 	QPoint origin = QLineF (v0p, v1p).pointAt (0.5).toPoint();
 	painter.drawText (origin, label);
 }