diff --git a/eeschema/sim/sim_plot_frame.cpp b/eeschema/sim/sim_plot_frame.cpp
index 7b743c451f..7bb20391d0 100644
--- a/eeschema/sim/sim_plot_frame.cpp
+++ b/eeschema/sim/sim_plot_frame.cpp
@@ -305,8 +305,6 @@ WINDOW_SETTINGS* SIM_PLOT_FRAME::GetWindowSettings( APP_SETTINGS_BASE* aCfg )
 
 void SIM_PLOT_FRAME::initWorkbook()
 {
-    m_workbook->DeleteAllPages();
-
     if( !m_simulator->Settings()->GetWorkbookFilename().IsEmpty() )
     {
         wxFileName filename = m_simulator->Settings()->GetWorkbookFilename();
diff --git a/eeschema/sim/sim_workbook.cpp b/eeschema/sim/sim_workbook.cpp
index 58db230f36..6c39c89ef7 100644
--- a/eeschema/sim/sim_workbook.cpp
+++ b/eeschema/sim/sim_workbook.cpp
@@ -27,12 +27,14 @@
 
 SIM_WORKBOOK::SIM_WORKBOOK() : wxAuiNotebook()
 {
+    m_modified = false;
 }
 
 
 SIM_WORKBOOK::SIM_WORKBOOK( wxWindow* aParent, wxWindowID aId, const wxPoint& aPos, const wxSize&
         aSize, long aStyle ) : wxAuiNotebook( aParent, aId, aPos, aSize, aStyle )
 {
+    m_modified = false;
 }