Index: src/OFLHAArchive.m
==================================================================
--- src/OFLHAArchive.m
+++ src/OFLHAArchive.m
@@ -482,11 +482,11 @@
 		@throw [OFOutOfRangeException exception];
 
 	@try {
 		[_stream writeBuffer: buffer length: length];
 	} @catch (OFWriteFailedException *e) {
-		OFEnsure(e.bytesWritten < length);
+		OFEnsure(e.bytesWritten <= length);
 
 		_bytesWritten += (uint32_t)e.bytesWritten;
 		_CRC16 = OFCRC16(_CRC16, buffer, e.bytesWritten);
 
 		if (e.errNo == EWOULDBLOCK)

Index: src/OFStream.m
==================================================================
--- src/OFStream.m
+++ src/OFStream.m
@@ -1073,11 +1073,11 @@
 		OFFreeMemory(_writeBuffer);
 		_writeBuffer = NULL;
 		_writeBufferLength = 0;
 	}
 
-	OFEnsure(bytesWritten < _writeBufferLength);
+	OFEnsure(bytesWritten <= _writeBufferLength);
 
 	memmove(_writeBuffer, _writeBuffer + bytesWritten,
 	    _writeBufferLength - bytesWritten);
 	_writeBufferLength -= bytesWritten;
 	@try {

Index: src/OFTarArchive.m
==================================================================
--- src/OFTarArchive.m
+++ src/OFTarArchive.m
@@ -438,10 +438,12 @@
 		@throw [OFOutOfRangeException exception];
 
 	@try {
 		[_stream writeBuffer: buffer length: length];
 	} @catch (OFWriteFailedException *e) {
+		OFEnsure(e.bytesWritten <= length);
+
 		_toWrite -= e.bytesWritten;
 
 		if (e.errNo == EWOULDBLOCK)
 			return e.bytesWritten;
 

Index: src/OFZIPArchive.m
==================================================================
--- src/OFZIPArchive.m
+++ src/OFZIPArchive.m
@@ -886,11 +886,11 @@
 		@throw [OFOutOfRangeException exception];
 
 	@try {
 		[_stream writeBuffer: buffer length: length];
 	} @catch (OFWriteFailedException *e) {
-		OFEnsure(e.bytesWritten < length);
+		OFEnsure(e.bytesWritten <= length);
 
 		_bytesWritten += (int64_t)e.bytesWritten;
 		_CRC32 = OFCRC32(_CRC32, buffer, e.bytesWritten);
 
 		if (e.errNo == EWOULDBLOCK)