diff --git a/util/MP4/box_afrt.cpp b/util/MP4/box_afrt.cpp
index 66c18b43..979f35be 100644
--- a/util/MP4/box_afrt.cpp
+++ b/util/MP4/box_afrt.cpp
@@ -83,7 +83,7 @@ void Box_afrt::WriteContent( ) {
     serializedFragmentEntries.append((char*)Box::uint32_to_uint8(FragmentRunEntryTable[i].FirstFragment),4);
     serializedFragmentEntries.append((char*)Box::uint32_to_uint8(0),4);
     serializedFragmentEntries.append((char*)Box::uint32_to_uint8(FragmentRunEntryTable[i].FirstFragmentTimestamp),4);
-    serializedFragmentEntries.append((char*)Box::uint32_to_uint8(FragmentRunEntryTable[i].FragmentDuration)),4;
+    serializedFragmentEntries.append((char*)Box::uint32_to_uint8(FragmentRunEntryTable[i].FragmentDuration),4);
     if(FragmentRunEntryTable[i].FragmentDuration == 0) {
     serializedFragmentEntries.append((char*)Box::uint8_to_uint8(FragmentRunEntryTable[i].DiscontinuityIndicator),1);
     }