Index: src/OFTarArchive.m
==================================================================
--- src/OFTarArchive.m
+++ src/OFTarArchive.m
@@ -14,12 +14,10 @@
  * file.
  */
 
 #include "config.h"
 
-#include <inttypes.h>
-
 #import "OFTarArchive.h"
 #import "OFTarArchiveEntry.h"
 #import "OFTarArchiveEntry+Private.h"
 #import "OFStream.h"
 #import "OFDate.h"
@@ -56,24 +54,10 @@
 
 - initWithStream: (OFStream *)stream
 	   entry: (OFTarArchiveEntry *)entry;
 @end
 
-static void
-stringToBuffer(unsigned char *buffer, OFString *string, size_t length)
-{
-	size_t UTF8StringLength = [string UTF8StringLength];
-
-	if (UTF8StringLength > length)
-		@throw [OFOutOfRangeException exception];
-
-	memcpy(buffer, [string UTF8String], UTF8StringLength);
-
-	for (size_t i = UTF8StringLength; i < length; i++)
-		buffer[i] = '\0';
-}
-
 @implementation OFTarArchive: OFObject
 + (instancetype)archiveWithStream: (OF_KINDOF(OFStream *))stream
 			     mode: (OFString *)mode
 {
 	return [[[self alloc] initWithStream: stream
@@ -227,13 +211,10 @@
 }
 
 - (OFStream *)streamForWritingEntry: (OFTarArchiveEntry *)entry
 {
 	void *pool;
-	uint64_t modificationDate;
-	unsigned char buffer[512];
-	uint16_t checksum = 0;
 
 	if (_mode != OF_TAR_ARCHIVE_MODE_WRITE &&
 	    _mode != OF_TAR_ARCHIVE_MODE_APPEND)
 		@throw [OFInvalidArgumentException exception];
 
@@ -241,50 +222,11 @@
 
 	[_lastReturnedStream close];
 	[_lastReturnedStream release];
 	_lastReturnedStream = nil;
 
-	stringToBuffer(buffer, [entry fileName], 100);
-	stringToBuffer(buffer + 100,
-	    [OFString stringWithFormat: @"%06" PRIo32 " ", [entry mode]], 8);
-	memcpy(buffer + 108, "000000 \0" "000000 \0", 16);
-	stringToBuffer(buffer + 124,
-	    [OFString stringWithFormat: @"%011" PRIo64 " ", [entry size]], 12);
-	modificationDate = [[entry modificationDate] timeIntervalSince1970];
-	stringToBuffer(buffer + 136,
-	    [OFString stringWithFormat: @"%011" PRIo64 " ", modificationDate],
-	    12);
-
-	/*
-	 * During checksumming, the checksum field is expected to be set to 8
-	 * spaces.
-	 */
-	memset(buffer + 148, ' ', 8);
-
-	buffer[156] = [entry type];
-	stringToBuffer(buffer + 157, [entry targetFileName], 100);
-
-	/* ustar */
-	memcpy(buffer + 257, "ustar\0" "00", 8);
-	stringToBuffer(buffer + 265, [entry owner], 32);
-	stringToBuffer(buffer + 297, [entry group], 32);
-	stringToBuffer(buffer + 329,
-	    [OFString stringWithFormat: @"%06" PRIo32 " ", [entry deviceMajor]],
-	    8);
-	stringToBuffer(buffer + 337,
-	    [OFString stringWithFormat: @"%06" PRIo32 " ", [entry deviceMinor]],
-	    8);
-	memset(buffer + 345, '\0', 155 + 12);
-
-	/* Fill in the checksum */
-	for (size_t i = 0; i < 500; i++)
-		checksum += buffer[i];
-	stringToBuffer(buffer + 148,
-	    [OFString stringWithFormat: @"%06" PRIo16, checksum], 7);
-
-	[_stream writeBuffer: buffer
-		      length: sizeof(buffer)];
+	[entry of_writeToStream: _stream];
 
 	_lastReturnedStream = [[OFTarArchive_FileWriteStream alloc]
 	    initWithStream: _stream
 		     entry: entry];
 

Index: src/OFTarArchiveEntry+Private.h
==================================================================
--- src/OFTarArchiveEntry+Private.h
+++ src/OFTarArchiveEntry+Private.h
@@ -15,12 +15,15 @@
  */
 
 #import "OFTarArchiveEntry.h"
 
 OF_ASSUME_NONNULL_BEGIN
+
+@class OFStream;
 
 @interface OFTarArchiveEntry ()
 - (instancetype)of_initWithHeader: (char [_Nonnull 512])header
     OF_METHOD_FAMILY(init);
+- (void)of_writeToStream: (OFStream *)stream;
 @end
 
 OF_ASSUME_NONNULL_END

Index: src/OFTarArchiveEntry.m
==================================================================
--- src/OFTarArchiveEntry.m
+++ src/OFTarArchiveEntry.m
@@ -33,10 +33,24 @@
 			length = i;
 
 	return [OFString stringWithUTF8String: buffer
 				       length: length];
 }
+
+static void
+stringToBuffer(unsigned char *buffer, OFString *string, size_t length)
+{
+	size_t UTF8StringLength = [string UTF8StringLength];
+
+	if (UTF8StringLength > length)
+		@throw [OFOutOfRangeException exception];
+
+	memcpy(buffer, [string UTF8String], UTF8StringLength);
+
+	for (size_t i = UTF8StringLength; i < length; i++)
+		buffer[i] = '\0';
+}
 
 static uintmax_t
 octalValueFromBuffer(const char *buffer, size_t length, uintmax_t max)
 {
 	uintmax_t value = [stringFromBuffer(buffer, length) octalValue];
@@ -241,6 +255,52 @@
 
 	objc_autoreleasePoolPop(pool);
 
 	return [ret autorelease];
 }
+
+- (void)of_writeToStream: (OFStream *)stream
+{
+	unsigned char buffer[512];
+	uint64_t modificationDate;
+	uint16_t checksum = 0;
+
+	stringToBuffer(buffer, _fileName, 100);
+	stringToBuffer(buffer + 100,
+	    [OFString stringWithFormat: @"%06" PRIo32 " ", _mode], 8);
+	memcpy(buffer + 108, "000000 \0" "000000 \0", 16);
+	stringToBuffer(buffer + 124,
+	    [OFString stringWithFormat: @"%011" PRIo64 " ", _size], 12);
+	modificationDate = [_modificationDate timeIntervalSince1970];
+	stringToBuffer(buffer + 136,
+	    [OFString stringWithFormat: @"%011" PRIo64 " ", modificationDate],
+	    12);
+
+	/*
+	 * During checksumming, the checksum field is expected to be set to 8
+	 * spaces.
+	 */
+	memset(buffer + 148, ' ', 8);
+
+	buffer[156] = _type;
+	stringToBuffer(buffer + 157, _targetFileName, 100);
+
+	/* ustar */
+	memcpy(buffer + 257, "ustar\0" "00", 8);
+	stringToBuffer(buffer + 265, _owner, 32);
+	stringToBuffer(buffer + 297, _group, 32);
+	stringToBuffer(buffer + 329,
+	    [OFString stringWithFormat: @"%06" PRIo32 " ", _deviceMajor], 8);
+	stringToBuffer(buffer + 337,
+	    [OFString stringWithFormat: @"%06" PRIo32 " ", _deviceMinor], 8);
+	memset(buffer + 345, '\0', 155 + 12);
+
+	/* Fill in the checksum */
+	for (size_t i = 0; i < 500; i++)
+		checksum += buffer[i];
+	stringToBuffer(buffer + 148,
+	    [OFString stringWithFormat: @"%06" PRIo16, checksum], 7);
+
+	[stream writeBuffer: buffer
+		     length: sizeof(buffer)];
+}
 @end