diff -up aqsis-1.4.2/texturing/texlib/tiffoutputfile.cpp.pisql_tiff aqsis-1.4.2/texturing/texlib/tiffoutputfile.cpp
--- aqsis-1.4.2/texturing/texlib/tiffoutputfile.cpp.pisql_tiff	2009-01-21 22:12:32.000000000 +0100
+++ aqsis-1.4.2/texturing/texlib/tiffoutputfile.cpp	2009-02-03 13:00:13.000000000 +0100
@@ -26,6 +26,8 @@
 
 #include "tiffoutputfile.h"
 
+#include <cstring>  // for memcpy()
+
 #include <boost/scoped_array.hpp>
 
 #include "aqsismath.h"
@@ -111,10 +113,16 @@ void CqTiffOutputFile::writeScanlinePixe
 	const TqUint8* rawBuf = buffer.rawData();
 	const TqInt rowStride = buffer.channelList().bytesPerPixel()*buffer.width();
 	const TqInt endLine = m_currentLine + buffer.height();
+	// Temporary buffer for scanlines.  We need to copy the data into here
+	// since libtiff trashes the buffer when encoding is turned on.  (The TIFF
+	// docs don't seem to mention this though, ugh.)
+	boost::scoped_array<TqUint8> lineBuf(new TqUint8[rowStride]);
 	for(TqInt line = m_currentLine; line < endLine; ++line)
 	{
-		TIFFWriteScanline( dirHandle.tiffPtr(),
-				reinterpret_cast<tdata_t>(const_cast<TqUint8*>(rawBuf)),
+		// copy the data into temp buffer.
+		std::memcpy(lineBuf.get(), rawBuf, rowStride);
+		// write data
+		TIFFWriteScanline( dirHandle.tiffPtr(), reinterpret_cast<tdata_t>(lineBuf.get()),
 				static_cast<uint32>(line) );
 		rawBuf += rowStride;
 	}