diff --git a/src/simulation_widget.cc b/src/simulation_widget.cc
index eead754..5ccb854 100644
--- a/src/simulation_widget.cc
+++ b/src/simulation_widget.cc
@@ -223,7 +223,7 @@ SimulationWidget::draw_grid(cairo_t* ctx)
   // useful constants
   const History& hist              = _simulation->get_history();
 
-  const unsigned int hist_front    = hist.get_front();
+  const unsigned int hist_front    = hist.get_front() == 0 ? 0 : hist.get_front() - 1;
   const double top_margin          = _yu_top_margin * _y_unit;
   // const double left_margin         = _x_unit;
   const double left_graph_margin   = _xu_left_graph_margin * _x_unit;
@@ -302,7 +302,7 @@ SimulationWidget::draw_bars(cairo_t* ctx)
 
   // useful constants
   const History& hist              = _simulation->get_history();
-  const unsigned int hist_front    = hist.get_front();
+  unsigned int hist_front          = hist.get_front();
   const double top_margin          = _yu_top_margin * _y_unit;
   // const double left_margin         = _x_unit;
   const double left_graph_margin   = _xu_left_graph_margin * _x_unit;
@@ -328,6 +328,13 @@ SimulationWidget::draw_bars(cairo_t* ctx)
     from_time = 1;
   }
 
+  // We draw the interval [0, front)
+  // so if front <= 1, we've nothing to draw
+  if(hist_front <= 1)
+    return;
+  else
+    hist_front--;
+
 #ifndef NDEBUG
   std::cout << " SimulationWidget::draw_bars from:" << from_time << "  to:" << hist_front << std::endl;
 #endif