diff --git a/ly/musicxml/ly2xml_mediator.py b/ly/musicxml/ly2xml_mediator.py
index a9ec6951..381ba521 100644
--- a/ly/musicxml/ly2xml_mediator.py
+++ b/ly/musicxml/ly2xml_mediator.py
@@ -290,7 +290,10 @@ def check_simultan(self):
             self.part.merge_voice(self.sections[-1])
         elif len(self.sections)>1:
              self.sections[-2].merge_voice(self.sections[-1])
-        self.sections.pop()
+
+        print("\n\nAchtung, sections: {}\n\n".format(self.sections))
+        if (len(self.sections) > 0):
+            self.sections.pop()
 
     def check_score(self):
         """