diff --git a/src/libslic3r/Technologies.hpp b/src/libslic3r/Technologies.hpp
index efb7ab486..1d4c63fb6 100644
--- a/src/libslic3r/Technologies.hpp
+++ b/src/libslic3r/Technologies.hpp
@@ -67,7 +67,7 @@
 // Enable project dirty state manager
 #define ENABLE_PROJECT_DIRTY_STATE (1 && ENABLE_2_4_0_ALPHA0)
 // Enable project dirty state manager debug window
-#define ENABLE_PROJECT_DIRTY_STATE_DEBUG_WINDOW (0 && ENABLE_PROJECT_DIRTY_STATE)
+#define ENABLE_PROJECT_DIRTY_STATE_DEBUG_WINDOW (1 && ENABLE_PROJECT_DIRTY_STATE)
 
 
 #endif // _prusaslicer_technologies_h_
diff --git a/src/slic3r/GUI/ProjectDirtyStateManager.cpp b/src/slic3r/GUI/ProjectDirtyStateManager.cpp
index 95cfa042e..30d41f808 100644
--- a/src/slic3r/GUI/ProjectDirtyStateManager.cpp
+++ b/src/slic3r/GUI/ProjectDirtyStateManager.cpp
@@ -210,8 +210,7 @@ void ProjectDirtyStateManager::reset_after_save()
 
     if (&main_stack == &active_stack) {
         const UndoRedo::Snapshot* saveable_snapshot = get_last_saveable_snapshot(EStackType::Main, main_stack, m_state.gizmos, m_last_save.main);
-        assert(saveable_snapshot != nullptr);
-        m_last_save.main = saveable_snapshot->timestamp;
+        m_last_save.main = (saveable_snapshot != nullptr) ? saveable_snapshot->timestamp : 0;
     }
     else {
         const UndoRedo::Snapshot* main_active_snapshot = get_active_snapshot(main_stack);