diff --git a/sleepyhead/Graphs/gGraph.cpp b/sleepyhead/Graphs/gGraph.cpp
index 1836ed8f..4c649121 100644
--- a/sleepyhead/Graphs/gGraph.cpp
+++ b/sleepyhead/Graphs/gGraph.cpp
@@ -167,6 +167,8 @@ gGraph::gGraph(QString name, gGraphView *graphview, QString title, QString units
     m_enforceMinY = m_enforceMaxY = false;
     m_showTitle = true;
     m_printing = false;
+
+    left = right = top = bottom = 0;
 }
 gGraph::~gGraph()
 {
diff --git a/sleepyhead/Graphs/gSessionTimesChart.cpp b/sleepyhead/Graphs/gSessionTimesChart.cpp
index 26a22919..8ee149b3 100644
--- a/sleepyhead/Graphs/gSessionTimesChart.cpp
+++ b/sleepyhead/Graphs/gSessionTimesChart.cpp
@@ -30,6 +30,9 @@ gSummaryChart::gSummaryChart(QString label, MachineType machtype)
     tz_offset = d2.secsTo(d1);
     tz_hours = tz_offset / 3600.0;
     expected_slices = 5;
+
+    idx_end = 0;
+    idx_start = 0;
 }
 
 gSummaryChart::gSummaryChart(ChannelID code, MachineType machtype)
@@ -47,6 +50,9 @@ gSummaryChart::gSummaryChart(ChannelID code, MachineType machtype)
     addCalc(code, ST_MID, brighten(schema::channel[code].defaultColor() ,1.20f));
     addCalc(code, ST_90P, brighten(schema::channel[code].defaultColor() ,1.70f));
     addCalc(code, ST_MAX, brighten(schema::channel[code].defaultColor() ,2.30f));
+
+    idx_end = 0;
+    idx_start = 0;
 }
 
 gSummaryChart::~gSummaryChart()