diff --git a/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx b/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx
index b558241711f..9faaf935529 100644
--- a/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx
+++ b/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx
@@ -213,6 +213,11 @@ void QVTKOpenGLNativeWidget::initializeGL()
   {
     Q_ASSERT(this->RenderWindowAdapter.data() == nullptr);
 
+    auto ostate = this->RenderWindow->GetState();
+    ostate->Reset();
+    // By default, Qt sets the depth function to GL_LESS but VTK expects GL_LEQUAL
+    ostate->vtkglDepthFunc(GL_LEQUAL);
+
     // When a QOpenGLWidget is told to use a QSurfaceFormat with samples > 0,
     // QOpenGLWidget doesn't actually create a context with multi-samples and
     // internally changes the QSurfaceFormat to be samples=0. Thus, we can't
diff --git a/GUISupport/Qt/QVTKOpenGLWindow.cxx b/GUISupport/Qt/QVTKOpenGLWindow.cxx
index c6398c0384d..b1e8d5bf9ed 100644
--- a/GUISupport/Qt/QVTKOpenGLWindow.cxx
+++ b/GUISupport/Qt/QVTKOpenGLWindow.cxx
@@ -203,6 +203,12 @@ void QVTKOpenGLWindow::initializeGL()
   if (this->RenderWindow)
   {
     Q_ASSERT(this->RenderWindowAdapter.data() == nullptr);
+
+    auto ostate = this->RenderWindow->GetState();
+    ostate->Reset();
+    // By default, Qt sets the depth function to GL_LESS but VTK expects GL_LEQUAL
+    ostate->vtkglDepthFunc(GL_LEQUAL);
+
     this->RenderWindowAdapter.reset(
       new QVTKRenderWindowAdapter(this->context(), this->RenderWindow, this));
     this->RenderWindowAdapter->setDefaultCursor(this->defaultCursor());