diff --git a/removeads.py b/removeads.py
index 457719b..cab5920 100755
--- a/removeads.py
+++ b/removeads.py
@@ -377,20 +377,39 @@ def changeEBMLElementSize(inputFile, position, addendum):
     logger.info('Found element at position: %d, size of type: %d  size of data: %d maximal size: %d.' % (initialPosition, typeSize, sizeOfData, maxSize))
     
     newSize = sizeOfData+addendum
+    delta = 0
     if  newSize > maxSize:
-        # TODO: we can reencode the header with a larger length field ...
-        logger.error('New size is too big to be encoded in actual size field.')
-        exit(-1)
+        # TODO: Test this code ...
+        newEncodedSize = getEBMLLength(newSize)
+        sizeOfNewEncodedSize = len(newEncodedSize)
+        if sizeOfNewEncodedSize <= sizeOfDataSize:
+            logger.error('New encoded size is smaller (%d) or equal than previous size (%d). This should not happen.' % (sizeOfNewEncodedSize, sizeOfDataSize))
+            exit(-1)
+        # The difference of length between old size field and new one.
+        delta = sizeOfNewEncodedSize - sizeOfDataSize
+        fileLength = fstat(infd).st_size 
+        # We seek after actual length field
+        lseek(infd, position+sizeOfDataSize, SEEK_SET)
+        # We read the rest of file
+        tail = read(infd, fileLength-(position+sizeOfDataSize))
+        # We increase file length
+        ftruncate(infd, fileLength+delta)
+        # We go to the beginning of length field
+        lseek(infd, position, SEEK_SET)
+        # We write the new length field
+        write(infd, newEncodedSize)
+        # We overwrite the rest of file with its previous content that has been offset.
+        write(infd, tail)
+    else:
+        size = newSize + ((128>>(sizeOfDataSize-1))<<((sizeOfDataSize-1)*8))
+        newSizeBuf = (size).to_bytes(sizeOfDataSize, byteorder='big')
 
-    size = newSize + ((128>>(sizeOfDataSize-1))<<((sizeOfDataSize-1)*8))
-    newSizeBuf = (size).to_bytes(sizeOfDataSize, byteorder='big')
-
-    logger.info('Old encoded size: %s New encoded size: %s' % (hexdump.dump(oldSizeBuf,sep=':'), hexdump.dump(newSizeBuf, sep=':')))
-    lseek(infd, position, SEEK_SET)
-    write(infd, newSizeBuf)
+        logger.info('Old encoded size: %s New encoded size: %s' % (hexdump.dump(oldSizeBuf,sep=':'), hexdump.dump(newSizeBuf, sep=':')))
+        lseek(infd, position, SEEK_SET)
+        write(infd, newSizeBuf)
     
-    # TODO: we will return the increase of length of the modified element (if its new size does not fit the older one)
-    return 0
+    # We return the potential increase in size of the file if the length field had to be increased.
+    return delta
 
 def changeCodecPrivateData(mkvinfo, inputFile, codecData):
     logger = logging.getLogger(__name__)