diff --git a/src/blocks/scratch3_looks.js b/src/blocks/scratch3_looks.js
index 7f6388b39..5fc16085c 100644
--- a/src/blocks/scratch3_looks.js
+++ b/src/blocks/scratch3_looks.js
@@ -153,13 +153,16 @@ class Scratch3LooksBlocks {
      * @private
      */
     _renderBubble (target) {
+        if (!this.runtime.renderer) return;
+
         const bubbleState = this._getBubbleState(target);
         const {drawableVisible, type, text, onSpriteRight} = bubbleState;
 
         // Remove the bubble if target is not visible, or text is being set to blank
         // without being initialized. See comment below about blank text optimization.
         if (!target.visible || (text === '' && !bubbleState.skinId)) {
-            return this._onTargetWillExit(target);
+            this._onTargetWillExit(target);
+            return;
         }
 
         if (bubbleState.skinId) {
diff --git a/src/engine/sequencer.js b/src/engine/sequencer.js
index 2db6054b7..ce65163d4 100644
--- a/src/engine/sequencer.js
+++ b/src/engine/sequencer.js
@@ -175,7 +175,7 @@ class Sequencer {
             thread.popStack();
         }
         // Save the current block ID to notice if we did control flow.
-        while ((currentBlockId = thread.peekStack()) !== 0) {
+        while ((currentBlockId = thread.peekStack())) {
             let isWarpMode = thread.peekStackFrame().warpMode;
             if (isWarpMode && !thread.warpTimer) {
                 // Initialize warp-mode timer if it hasn't been already.
diff --git a/test/fixtures/saythink-and-wait.sb2 b/test/fixtures/saythink-and-wait.sb2
new file mode 100644
index 000000000..d9be202c4
Binary files /dev/null and b/test/fixtures/saythink-and-wait.sb2 differ
diff --git a/test/integration/saythink-and-wait.js b/test/integration/saythink-and-wait.js
new file mode 100644
index 000000000..abde2d978
--- /dev/null
+++ b/test/integration/saythink-and-wait.js
@@ -0,0 +1,37 @@
+const Worker = require('tiny-worker');
+const path = require('path');
+const test = require('tap').test;
+const makeTestStorage = require('../fixtures/make-test-storage');
+const extract = require('../fixtures/extract');
+const VirtualMachine = require('../../src/index');
+const dispatch = require('../../src/dispatch/central-dispatch');
+
+const uri = path.resolve(__dirname, '../fixtures/saythink-and-wait.sb2');
+const project = extract(uri);
+
+// By default Central Dispatch works with the Worker class built into the browser. Tell it to use TinyWorker instead.
+dispatch.workerClass = Worker;
+
+test('say/think and wait', t => {
+    const vm = new VirtualMachine();
+    vm.attachStorage(makeTestStorage());
+
+    // Start VM, load project, and run
+    t.doesNotThrow(() => {
+        vm.start();
+        vm.clear();
+        vm.setCompatibilityMode(false);
+        vm.setTurboMode(false);
+        vm.loadProject(project).then(() => {
+            vm.greenFlag();
+
+            // After two seconds, stop the project.
+            // The test will fail if the project throws.
+            setTimeout(() => {
+                vm.stopAll();
+                t.end();
+                process.nextTick(process.exit);
+            }, 2000);
+        });
+    });
+});