diff --git a/blocks_vertical/data.js b/blocks_vertical/data.js
index 726697d47d..3dccdb3efb 100644
--- a/blocks_vertical/data.js
+++ b/blocks_vertical/data.js
@@ -46,6 +46,7 @@ Blockly.Blocks['data_variable'] = {
           "variableType": ""
         }
       ],
+      "output": null,
       "category": Blockly.Categories.data,
       "checkboxInFlyout": true,
       "extensions": ["contextMenu_getVariableBlock", "colours_data", "output_string"]