diff --git a/packages/blockly/core/options.ts b/packages/blockly/core/options.ts
index cc368d16bab..8c9b7e86517 100644
--- a/packages/blockly/core/options.ts
+++ b/packages/blockly/core/options.ts
@@ -147,7 +147,7 @@ export class Options {
     const rawOneBasedIndex = options['oneBasedIndex'];
     const oneBasedIndex =
       rawOneBasedIndex === undefined ? true : rawOneBasedIndex;
-    const renderer = options['renderer'] || 'geras';
+    const renderer = options['renderer'] || 'thrasos';
 
     const plugins = options['plugins'] || {};
 
diff --git a/packages/blockly/tests/mocha/insertion_marker_test.js b/packages/blockly/tests/mocha/insertion_marker_test.js
index f8215a847eb..8bcbb90dbe2 100644
--- a/packages/blockly/tests/mocha/insertion_marker_test.js
+++ b/packages/blockly/tests/mocha/insertion_marker_test.js
@@ -13,7 +13,7 @@ import {
 suite('InsertionMarkers', function () {
   setup(function () {
     sharedTestSetup.call(this);
-    this.workspace = Blockly.inject('blocklyDiv', {});
+    this.workspace = Blockly.inject('blocklyDiv', {renderer: 'geras'});
     Blockly.defineBlocksWithJsonArray([
       {
         'type': 'stack_block',
diff --git a/packages/docs/docs/codelabs/custom-renderer/observe-the-built-in-renderers.mdx b/packages/docs/docs/codelabs/custom-renderer/observe-the-built-in-renderers.mdx
index 6fc617432f0..39cb07b6f76 100644
--- a/packages/docs/docs/codelabs/custom-renderer/observe-the-built-in-renderers.mdx
+++ b/packages/docs/docs/codelabs/custom-renderer/observe-the-built-in-renderers.mdx
@@ -8,4 +8,4 @@ description: Introduction to the built-in renderers.
 
 First, visit [the advanced playground](https://blockly-demo.appspot.com/static/tests/playgrounds/advanced_playground.html) to observe what the built-in renderers look like.
 
-Click on the "Loops" entry and drag out a repeat block. Now, change the selection in the "renderer" drop down to observe the look of each built-in renderer. By default, the renderer named "Geras" is used.
+Click on the "Loops" entry and drag out a repeat block. Now, change the selection in the "renderer" drop down to observe the look of each built-in renderer. By default, the renderer named "Thrasos" is used.
diff --git a/packages/docs/docs/guides/configure/configuration_struct.mdx b/packages/docs/docs/guides/configure/configuration_struct.mdx
index 3c3dd06ccf0..e1706309563 100644
--- a/packages/docs/docs/guides/configure/configuration_struct.mdx
+++ b/packages/docs/docs/guides/configure/configuration_struct.mdx
@@ -57,7 +57,7 @@ default value based on whether the provided toolbox has categories or not.
 | `oneBasedIndex`       | boolean             | If `true` list and string operations should index from `1`, if `false` index from `0`. Defaults to `true`.                                                                                                                                                                                                                                                                                                                       |
 | `plugins`             | object              | An object mapping registry type names to replacement classes or the registered names of replacement classes. See [Inject your replacement class][replacement].                                                                                                                                                                                                                                                                   |
 | `readOnly`            | boolean             | If `true`, prevent the user from editing. Suppresses the toolbox and trashcan. Defaults to `false`. See also [`setIsReadOnly`][setIsReadOnly] and [`isReadOnly`][isReadOnly].                                                                                                                                                                                                                                                    |
-| `renderer`            | string              | Determines the renderer used by blockly. Pre-packaged renderers include `'geras'` (the default), `'thrasos'`, and `'zelos'` (a Scratch-like renderer). For information about custom renderers, see [Create custom renderers][renderer].                                                                                                                                                                                          |
+| `renderer`            | string              | Determines the renderer used by blockly. Pre-packaged renderers include `'thrasos'` (the default), `'geras'` (an older style we no longer recommend), and `'zelos'` (a Scratch-like renderer). For information about custom renderers, see [Create custom renderers][renderer].                                                                                                                                                                                          |
 | `rtl`                 | boolean             | If `true`, mirror the editor (for Arabic or Hebrew locales).See [RTL demo]. Defaults to `false`.                                                                                                                                                                                                                                                                                                                                 |
 | `scrollbars`          | object or boolean   | Sets whether the workspace has vertical or horizontal scrollbars. Takes an object where the `horizontal` property determines if horizontal scrolling is enabled and the `vertical` property determines if vertical scrolling is enabled. If a boolean is passed then it is equivalent to passing an object with both `horizontal` and `vertical` properties set as that value. Defaults to `true` if the toolbox has categories. |
 | `sounds`              | boolean             | If `false`, disables sounds. Defaults to `true`.                                                                                                                                                                                                                                                                                                                                                                                 |