diff --git a/nii2dt/nii2dt.pl b/nii2dt/nii2dt.pl
index 46787d9..a5d9457 100644
--- a/nii2dt/nii2dt.pl
+++ b/nii2dt/nii2dt.pl
@@ -273,6 +273,8 @@
 system("$antsDir/ImageMath 3 ${outputDir}/${outputFileRoot}rd.nii.gz TensorRadialDiffusion ${outputDir}/${outputFileRoot}dt.nii.gz");
 system("$antsDir/ImageMath 3 ${outputDir}/${outputFileRoot}rgb.nii.gz TensorColor ${outputDir}/${outputFileRoot}dt.nii.gz");
 
+# Copy ref image to output directory
+system("cp $ref ${outputDir}/${outputFileRoot}ref.nii.gz");
 
 # cleanup
 if ($cleanup) {