diff --git a/core/scratch_blocks_utils.js b/core/scratch_blocks_utils.js
index efb11ce634..ab05555d0a 100644
--- a/core/scratch_blocks_utils.js
+++ b/core/scratch_blocks_utils.js
@@ -84,7 +84,7 @@ Blockly.scratchBlocksUtils.changeObscuredShadowIds = function(block) {
  */
 Blockly.scratchBlocksUtils.isShadowArgumentReporter = function(block) {
   return (block.isShadow() && (block.type == 'argument_reporter_boolean' ||
-      block.type == 'argument_reporter_string_number' || block.isShadowArgument));
+      block.type == 'argument_reporter_string_number' || block.isShadowArgument_));
 };
 
 /**