diff --git a/libs/ardour/import.cc b/libs/ardour/import.cc
index 656e8f7f76..ae5f751767 100644
--- a/libs/ardour/import.cc
+++ b/libs/ardour/import.cc
@@ -234,7 +234,9 @@ write_audio_data_to_new_files (ImportableSource* source, ImportStatus& status,
 	const framecnt_t nframes = ResampledImportableSource::blocksize;
 	boost::shared_ptr<AudioFileSource> afs;
 	uint32_t channels = source->channels();
-	assert(channels > 0);
+	if (channels == 0) {
+		return;
+	}
 
 	boost::scoped_array<float> data(new float[nframes * channels]);
 	vector<boost::shared_array<Sample> > channel_data;