diff --git a/src/output/output_mp4.cpp b/src/output/output_mp4.cpp
index 9ba6b522..5a15d062 100644
--- a/src/output/output_mp4.cpp
+++ b/src/output/output_mp4.cpp
@@ -1350,7 +1350,7 @@ namespace Mist{
 
     // The remainder of this function handles non-live situations
     if (M.getLive()){
-      sortSet.erase(sortSet.begin());
+      if (sortSet.size()){sortSet.erase(sortSet.begin());}
       return;
     }