Index: src/OFLHAArchive.h
==================================================================
--- src/OFLHAArchive.h
+++ src/OFLHAArchive.h
@@ -37,10 +37,12 @@
 	OFLHAArchiveEntry *_Nullable _currentEntry;
 #ifdef OF_LHA_ARCHIVE_M
 @public
 #endif
 	OFStream *_Nullable _lastReturnedStream;
+@protected
+	bool _hasWritten;
 }
 
 /**
  * @brief The encoding to use for the archive. Defaults to ISO 8859-1.
  */

Index: src/OFLHAArchive.m
==================================================================
--- src/OFLHAArchive.m
+++ src/OFLHAArchive.m
@@ -123,11 +123,17 @@
 		if ((_mode == modeWrite || _mode == modeAppend) &&
 		    ![_stream isKindOfClass: [OFSeekableStream class]])
 			@throw [OFInvalidArgumentException exception];
 
 		if (_mode == modeAppend)
-			[(OFSeekableStream *)_stream seekToOffset: 0
+			/*
+			 * Only works with properly zero-terminated files that
+			 * have no trailing garbage. Unfortunately there is no
+			 * good way to check for this other than reading the
+			 * entire archive.
+			 */
+			[(OFSeekableStream *)_stream seekToOffset: -1
 							   whence: OFSeekEnd];
 
 		_encoding = OFStringEncodingISO8859_1;
 	} @catch (id e) {
 		[self release];
@@ -276,10 +282,11 @@
 	_lastReturnedStream = [[[OFLHAArchiveFileWriteStream alloc]
 	    of_initWithArchive: self
 			stream: (OFSeekableStream *)_stream
 			 entry: entry
 		      encoding: _encoding] autorelease];
+	_hasWritten = true;
 
 	return _lastReturnedStream;
 }
 
 - (void)close
@@ -288,12 +295,17 @@
 		@throw [OFNotOpenException exceptionWithObject: self];
 
 	@try {
 		[_lastReturnedStream close];
 	} @catch (OFNotOpenException *e) {
-		/* Might have already been closed by the user - that's fine. */
+		/* Might have already been closed by the user - that's fine */
 	}
+
+	/* LHA archives should be terminated with a header of size 0 */
+	if (_hasWritten)
+		[_stream writeBuffer: "" length: 1];
+
 	_lastReturnedStream = nil;
 
 	[_stream release];
 	_stream = nil;
 }