diff --git a/src/asfvideo.cpp b/src/asfvideo.cpp
index 21e7e8f2..6faa271e 100644
--- a/src/asfvideo.cpp
+++ b/src/asfvideo.cpp
@@ -252,9 +252,14 @@ AsfVideo::HeaderReader::HeaderReader(BasicIo::UniquePtr& io) : IdBuf_(GUID) {
 }
 
 void AsfVideo::decodeBlock() {
-  Internal::enforce(GUID + io_->tell() < io_->size(), Exiv2::ErrorCode::kerCorruptedMetadata);
-  HeaderReader others(io_);
-  auto tag = GUIDReferenceTags.find(GUIDTag(others.getId().data()));
+  Internal::enforce(GUID + QWORD + io_->tell() <= io_->size(), Exiv2::ErrorCode::kerCorruptedMetadata);
+  HeaderReader objectHeader(io_);
+#ifdef EXIV2_DEBUG_MESSAGES
+  EXV_INFO << "decodeBlock = " << GUIDTag(objectHeader.getId().data()).to_string()
+           << "\tsize= " << objectHeader.getSize() << "\t " << io_->tell() << "/" << io_->size() << std::endl;
+#endif
+  Internal::enforce(objectHeader.getSize() + io_->tell() <= io_->size(), Exiv2::ErrorCode::kerCorruptedMetadata);
+  auto tag = GUIDReferenceTags.find(GUIDTag(objectHeader.getId().data()));
 
   if (tag != GUIDReferenceTags.end()) {
     if (tag->second == "Header")
@@ -277,11 +282,12 @@ void AsfVideo::decodeBlock() {
       DegradableJPEGMedia();
     else  // tag found but not processed
     {
-      io_->seekOrThrow(io_->tell() + others.getRemainingSize(), BasicIo::beg, ErrorCode::kerFailedToReadImageData);
+      io_->seekOrThrow(io_->tell() + objectHeader.getRemainingSize(), BasicIo::beg,
+                       ErrorCode::kerFailedToReadImageData);
     }
   } else  // tag not found
   {
-    io_->seekOrThrow(io_->tell() + others.getRemainingSize(), BasicIo::beg, ErrorCode::kerFailedToReadImageData);
+    io_->seekOrThrow(io_->tell() + objectHeader.getRemainingSize(), BasicIo::beg, ErrorCode::kerFailedToReadImageData);
   }
 
 }  // AsfVideo::decodeBlock
@@ -481,7 +487,8 @@ void AsfVideo::fileProperties() {
   xmpData()["Xmp.video.SendDuration"] = readQWORDTag(io_);
   xmpData()["Xmp.video.Preroll"] = readQWORDTag(io_);
 
-  io_->seek(io_->tell() + DWORD + DWORD + DWORD, BasicIo::beg);
+  io_->seek(io_->tell() + DWORD + DWORD + DWORD,
+            BasicIo::beg);  // ignore Flags, Minimum Data Packet Size and Maximum Data Packet Size
   xmpData()["Xmp.video.MaxBitRate"] = readDWORDTag(io_);
 }  // AsfVideo::fileProperties