diff --git a/src/serialization/sb2.js b/src/serialization/sb2.js
index 5efd5c9da..9ca378d90 100644
--- a/src/serialization/sb2.js
+++ b/src/serialization/sb2.js
@@ -954,6 +954,12 @@ const parseBlock = function (sb2block, addBroadcastMsg, getVariableId, extension
             value: 'number'
         };
         break;
+    case 'costumeName':
+        activeBlock.fields.NUMBER_NAME = {
+            name: 'NUMBER_NAME',
+            value: 'name'
+        };
+        break;
     }
 
     // Special cases to generate mutations.
diff --git a/src/serialization/sb2_specmap.js b/src/serialization/sb2_specmap.js
index e22025285..5079c206f 100644
--- a/src/serialization/sb2_specmap.js
+++ b/src/serialization/sb2_specmap.js
@@ -428,6 +428,11 @@ const specMap = {
         argMap: [
         ]
     },
+    'costumeName': {
+        opcode: 'looks_costumenumbername',
+        argMap: [
+        ]
+    },
     'sceneName': {
         opcode: 'looks_backdropnumbername',
         argMap: [
diff --git a/test/unit/blocks_looks.js b/test/unit/blocks_looks.js
index c7b4c3d7b..a9602a706 100644
--- a/test/unit/blocks_looks.js
+++ b/test/unit/blocks_looks.js
@@ -34,8 +34,8 @@ test('getCostumeNumberName returns 1-indexed costume number', t => {
 test('getCostumeNumberName can return costume name', t => {
     util.target.currentCostume = 0; // This is 0-indexed.
     const args = {NUMBER_NAME: 'name'};
-    const number = blocks.getCostumeNumberName(args, util);
-    t.strictEqual(number, 'first name');
+    const name = blocks.getCostumeNumberName(args, util);
+    t.strictEqual(name, 'first name');
     t.end();
 });