diff --git a/src/GUI/gearratiograph.cpp b/src/GUI/gearratiograph.cpp
index 566be717..b482ce8c 100644
--- a/src/GUI/gearratiograph.cpp
+++ b/src/GUI/gearratiograph.cpp
@@ -60,7 +60,7 @@ QList<GraphItem*> GearRatioGraph::loadData(const Data &data)
 
 qreal GearRatioGraph::top() const
 {
-	qreal key, val;
+	qreal key = NAN, val = NAN;
 
 	for (QMap<qreal, qreal>::const_iterator it = _map.constBegin();
 	  it != _map.constEnd(); ++it) {
diff --git a/src/GUI/gearratiographitem.cpp b/src/GUI/gearratiographitem.cpp
index deab7983..64a10d82 100644
--- a/src/GUI/gearratiographitem.cpp
+++ b/src/GUI/gearratiographitem.cpp
@@ -5,7 +5,7 @@
 GearRatioGraphItem::GearRatioGraphItem(const Graph &graph, GraphType type,
   QGraphicsItem *parent) : GraphItem(graph, type, parent)
 {
-	qreal val;
+	qreal val = NAN;
 
 	for (int j = 1; j < graph.size(); j++) {
 		const GraphPoint &p = graph.at(j);