diff --git a/src/protocolP2P/FilePart.java b/src/protocolP2P/FilePart.java
index 1dd89ce..d4a3fb2 100644
--- a/src/protocolP2P/FilePart.java
+++ b/src/protocolP2P/FilePart.java
@@ -73,8 +73,8 @@ public class FilePart extends Payload {
 	 * @throws	InternalError
 	 */
 	protected byte[] toDatagram() throws InternalError {
-		//TODO : calculate payload size
-		int size = 24 + filename.length() + 1;
+		// compute payload size
+		int size = 28 + filename.length() + partialContent.length;
 		byte[] datagram = new byte[size]; // java initialize all to zero
 		// size is keep blank (ProtocolP2PDatagram will handle it)
 		// set request/response code
@@ -87,14 +87,22 @@ public class FilePart extends Payload {
 		BytesArrayTools.write(datagram, 16, totalSize);
 		// write filename’s size to datagram
 		BytesArrayTools.write(datagram, 24, filename.length());
-		//TODO : write filename to datagram
+		// write filename to datagram
 		try {
 			byte[] bFilename = filename.getBytes("UTF-8");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
-		//TODO : write partialContent to datagram
-
+		int i = filename.length() + 24;
+		for (byte b : bFilename) {
+			datagram[i] = b;
+			i += 1;
+		}
+		// write partialContent to datagram
+		for (byte b: partialContent) {
+			datagram[i] = b;
+			i += 1;
+		}
 		return datagram;
 	}
 
@@ -113,7 +121,7 @@ public class FilePart extends Payload {
 		totalSize = BytesArrayTools.readLong(datagram, 16);
 	}
 
-	/** Read filename’s size from bytes 24 to 28 of datagram.
+	/** Read filename’s size from bytes 24 to 27 of datagram.
 	 * @param datagram	received datagram
 	 * @throws	ProtocolError
 	 * @throws	SizeError
@@ -132,7 +140,7 @@ public class FilePart extends Payload {
 		return size;
 	}
 
-	/** Write filename from byte 24 to byte (24 + (filenameSize - 1)) of datagram.
+	/** Write filename from byte 28 to byte (28 + (filenameSize - 1)) of datagram.
 	 * @param datagram	received datagram
 	 * @throws	ProtocolError
 	 * @throws	SizeError
@@ -141,19 +149,19 @@ public class FilePart extends Payload {
 	private void setFilename(byte[] datagram) throws ProtocolError, SizeError, InternalError {
 		int filenameSize = getFilenameSize(datagram); // this can throw ProtocolError or SizeError
 		try {
-			filename = new String(datagram, 24, filenameSize, "UTF-8");
+			filename = new String(datagram, 28, filenameSize, "UTF-8");
 		} catch (UnsupportedEncodingException e) {
 			throw new InternalError();
 		}
 	}
 
-	/** Write partialContent from byte (24 + filenameSize) to byte (8 + payloadSize) of datagram.
+	/** Write partialContent from byte (28 + filenameSize) to byte (8 + payloadSize) of datagram.
 	 * @param datagram	received datagram
 	 * @throws	SizeError
 	 * @throws	ProtocolError
 	 */
 	private void setPartialContent(byte[] datagram) throws ProtocolError, SizeError {
-		int start = 24 + getFilenameSize(datagram); // this can throw SizeError or ProtocolError
+		int start = 28 + getFilenameSize(datagram); // this can throw SizeError or ProtocolError
 		int end = 8 + getPayloadSize(datagram); // this can throw SizeError
 		try {
 			partialContent = Arrays.copyOfRange(datagram, start, end+1);