diff --git a/descriptors/mrtrix/mrconvert.json b/descriptors/mrtrix/mrconvert.json
index ef2fc7cf2..8276b1354 100644
--- a/descriptors/mrtrix/mrconvert.json
+++ b/descriptors/mrtrix/mrconvert.json
@@ -82,7 +82,8 @@
       "type": "Number",
       "optional": true,
       "integer": true,
-      "list": true
+      "list": true,
+      "list-seperator": ","
     },
     {
       "id": "scaling",
diff --git a/extraction/mrtrix/mrt2bt.js b/extraction/mrtrix/mrt2bt.js
index 632d895e4..df127579b 100644
--- a/extraction/mrtrix/mrt2bt.js
+++ b/extraction/mrtrix/mrt2bt.js
@@ -373,6 +373,9 @@ for (const file of fs.readdirSync(jsonPath)) {
             ]
           };
     }
+    else if (descriptor.name == 'mrconvert') {
+        descriptor.inputs[4]["list-seperator"] = ",";
+    }
 
     console.log(" done");