diff --git a/lib/dtsc.cpp b/lib/dtsc.cpp
index 0a8b64e1..30bb636f 100644
--- a/lib/dtsc.cpp
+++ b/lib/dtsc.cpp
@@ -2364,6 +2364,7 @@ namespace DTSC{
       t.parts.setInt(t.partDurationField, packTime - getLastms(tNumber), newPartNum);
     }else{
       t.parts.setInt(t.partDurationField, 0, newPartNum);
+      setFirstms(tNumber, packTime);
     }
     t.parts.addRecords(1);