diff -r -U3 OpenHantek6022.orig/openhantek/src/glscope.cpp OpenHantek6022/openhantek/src/glscope.cpp
--- OpenHantek6022.orig/openhantek/src/glscope.cpp	2019-05-06 13:11:41.474816511 +0300
+++ OpenHantek6022/openhantek/src/glscope.cpp	2019-05-06 13:11:18.862736954 +0300
@@ -611,6 +611,8 @@
     if (!scope->voltage[channel].used) return;
 
     m_program->setUniformValue(colorLocation, view->screen.voltage[channel].darker(100 + 10 * historyIndex));
+
+    if (channel >= graph.vaoVoltage.size()) return;
     Graph::VaoCount &v = graph.vaoVoltage[channel];
 
     QOpenGLVertexArrayObject::Binder b(v.first);