diff --git a/src/engine/blocks.js b/src/engine/blocks.js
index f8d8da0c138..8dd4df26333 100644
--- a/src/engine/blocks.js
+++ b/src/engine/blocks.js
@@ -824,7 +824,7 @@ class Blocks {
         // Delete comments attached to the block.
         if (block.comment) {
             const editingTarget = this.runtime.getEditingTarget();
-            if (editingTarget.comments.hasOwnProperty(block.comment)) {
+            if (editingTarget && editingTarget.comments.hasOwnProperty(block.comment)) {
                 delete editingTarget.comments[block.comment];
             }
         }
diff --git a/src/serialization/sb3.js b/src/serialization/sb3.js
index e309880371f..820e987fe1a 100644
--- a/src/serialization/sb3.js
+++ b/src/serialization/sb3.js
@@ -798,7 +798,7 @@ const deserializeFields = function (fields) {
  * work with pre-parsed deserialized blocks.
  *
  * @param {object} blocks Serialized SB3 "blocks" property of a target. Will be mutated.
- * @return {object} input is modified and returned
+ * @return {object} object that has "blocks" and "oldToNew" attributes
  */
 const deserializeBlocks = function (blocks) {
     // oldToNew is used to fix comments attached to variable blocks: see #1893
diff --git a/test/fixtures/variable-comment.sb3 b/test/fixtures/variable-comment.sb3
new file mode 100644
index 00000000000..18ef05f21b1
Binary files /dev/null and b/test/fixtures/variable-comment.sb3 differ
diff --git a/test/integration/variable-comment.js b/test/integration/variable-comment.js
new file mode 100644
index 00000000000..0c352056547
--- /dev/null
+++ b/test/integration/variable-comment.js
@@ -0,0 +1,53 @@
+const path = require('path');
+const test = require('tap').test;
+const makeTestStorage = require('../fixtures/make-test-storage');
+const readFileToBuffer = require('../fixtures/readProjectFile').readFileToBuffer;
+const VirtualMachine = require('../../src/index');
+
+const projectUri = path.resolve(__dirname, '../fixtures/variable-comment.sb3');
+const project = readFileToBuffer(projectUri);
+
+test('load an sb3 project with comments attached to variable blocks (#1893)', t => {
+    const vm = new VirtualMachine();
+    vm.attachStorage(makeTestStorage());
+
+    // Evaluate playground data and exit
+    vm.on('playgroundData', e => {
+        const threads = JSON.parse(e.threads);
+        t.equal(threads.length, 0);
+
+        const stage = vm.runtime.targets[0];
+        const stageComments = Object.values(stage.comments);
+
+        // Stage has 2 comments
+        t.equal(stageComments.length, 2);
+
+        // comment1 is atached to variable block
+        t.equal(stageComments[0].text, 'comment1');
+        const variableBlock = stage.blocks.getBlock(stageComments[0].blockId);
+        t.equal(variableBlock.opcode, 'data_variable');
+
+        // comment2 is atached to variable block
+        t.equal(stageComments[1].text, 'comment2');
+        const listBlock = stage.blocks.getBlock(stageComments[1].blockId);
+        t.equal(listBlock.opcode, 'data_listcontents');
+
+        t.end();
+        process.nextTick(process.exit);
+    });
+
+    // Start VM, load project, and run
+    t.doesNotThrow(() => {
+        vm.start();
+        vm.clear();
+        vm.setCompatibilityMode(false);
+        vm.setTurboMode(false);
+        vm.loadProject(project).then(() => {
+            vm.greenFlag();
+            setTimeout(() => {
+                vm.getPlaygroundData();
+                vm.stopAll();
+            }, 100);
+        });
+    });
+});
diff --git a/test/unit/engine_blocks.js b/test/unit/engine_blocks.js
index f4451aa39fb..80b99b06dea 100644
--- a/test/unit/engine_blocks.js
+++ b/test/unit/engine_blocks.js
@@ -600,6 +600,25 @@ test('delete inputs', t => {
     t.end();
 });
 
+test('delete block with comment', t => {
+    const b = new Blocks(new Runtime());
+    const fakeTarget = {
+        comments: {
+            bar: {
+                blockId: 'foo'
+            }
+        }
+    };
+    b.runtime.getEditingTarget = () => fakeTarget;
+    b.createBlock({
+        id: 'foo',
+        comment: 'bar'
+    });
+    b.deleteBlock('foo');
+    t.notOk(fakeTarget.comments.hasOwnProperty('bar'));
+    t.end();
+});
+
 test('updateAssetName function updates name in sound field', t => {
     const b = new Blocks(new Runtime());
     b.createBlock({
diff --git a/test/unit/sprites_rendered-target.js b/test/unit/sprites_rendered-target.js
index 681a10d86db..da4eb7dc6ef 100644
--- a/test/unit/sprites_rendered-target.js
+++ b/test/unit/sprites_rendered-target.js
@@ -45,6 +45,19 @@ test('blocks get new id on duplicate', t => {
     });
 });
 
+test('comments are duplicated when duplicating target', t => {
+    const r = new Runtime();
+    const s = new Sprite(null, r);
+    const rt = new RenderedTarget(s, r);
+    rt.createComment('commentid', null, 'testcomment', 0, 0, 100, 100, false);
+    t.ok(s.comments.hasOwnProperty('commentid'));
+    return rt.duplicate().then(duplicate => {
+        t.notOk(duplicate.comments.hasOwnProperty('commentid'));
+        t.ok(Object.keys(duplicate.comments).length === 1);
+        t.end();
+    });
+});
+
 test('direction', t => {
     const r = new Runtime();
     const s = new Sprite(null, r);