diff --git a/src/Converter.cpp b/src/Converter.cpp
index 8adcfc3258..1e3b15c380 100644
--- a/src/Converter.cpp
+++ b/src/Converter.cpp
@@ -307,7 +307,8 @@ bool Converters::convert(Buffer const * buffer,
 			LYXERR(Debug::FILES, "No converter defined! "
 				   "I use convertDefault.py:\n\t" << command);
 			Systemcall one;
-			one.startscript(Systemcall::Wait, command, buffer->filePath());
+			one.startscript(Systemcall::Wait, command, buffer ?
+					buffer->filePath() : string());
 			if (to_file.isReadableFile()) {
 				if (conversionflags & try_cache)
 					ConverterCache::get().add(orig_from,
@@ -444,13 +445,14 @@ bool Converters::convert(Buffer const * buffer,
 			if (dummy) {
 				res = one.startscript(Systemcall::DontWait,
 					to_filesystem8bit(from_utf8(command)),
-					buffer->filePath());
+					buffer ? buffer->filePath() : string());
 				// We're not waiting for the result, so we can't do anything
 				// else here.
 			} else {
 				res = one.startscript(Systemcall::Wait,
 						to_filesystem8bit(from_utf8(command)),
-						buffer->filePath());
+						buffer ? buffer->filePath()
+						       : string());
 				if (!real_outfile.empty()) {
 					Mover const & mover = getMover(conv.to);
 					if (!mover.rename(outfile, real_outfile))