diff --git a/examples/developer-tools/src/blocks/colour.ts b/examples/developer-tools/src/blocks/colour.ts
index d8a00c0e8e..840de4a0c4 100644
--- a/examples/developer-tools/src/blocks/colour.ts
+++ b/examples/developer-tools/src/blocks/colour.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * A hue-picker to set the colour of a block.
diff --git a/examples/developer-tools/src/blocks/factory_base.ts b/examples/developer-tools/src/blocks/factory_base.ts
index b331eacb12..b2131fb913 100644
--- a/examples/developer-tools/src/blocks/factory_base.ts
+++ b/examples/developer-tools/src/blocks/factory_base.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 export const factoryBase = {
   // Base of new block.
diff --git a/examples/developer-tools/src/blocks/fields.ts b/examples/developer-tools/src/blocks/fields.ts
index 728220a887..886cd2fe58 100644
--- a/examples/developer-tools/src/blocks/fields.ts
+++ b/examples/developer-tools/src/blocks/fields.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * Check to see if more than one field has this name.
diff --git a/examples/developer-tools/src/blocks/index.ts b/examples/developer-tools/src/blocks/index.ts
index af71d4451e..ca316a3380 100644
--- a/examples/developer-tools/src/blocks/index.ts
+++ b/examples/developer-tools/src/blocks/index.ts
@@ -5,7 +5,7 @@
  */
 
 import {factoryBase} from './factory_base';
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {input} from './input';
 import {type, typeGroup, typeGroupContainer, typeGroupItem} from './type';
 import {
diff --git a/examples/developer-tools/src/blocks/input.ts b/examples/developer-tools/src/blocks/input.ts
index 79b3043375..478b4c2083 100644
--- a/examples/developer-tools/src/blocks/input.ts
+++ b/examples/developer-tools/src/blocks/input.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * Check to see if more than one input has this name.
diff --git a/examples/developer-tools/src/blocks/type.ts b/examples/developer-tools/src/blocks/type.ts
index 378f7ec0be..543340e754 100644
--- a/examples/developer-tools/src/blocks/type.ts
+++ b/examples/developer-tools/src/blocks/type.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 interface TypeState {
   typeCount: number;
diff --git a/examples/developer-tools/src/index.ts b/examples/developer-tools/src/index.ts
index 0ec33f7581..46dbff8dea 100644
--- a/examples/developer-tools/src/index.ts
+++ b/examples/developer-tools/src/index.ts
@@ -4,7 +4,9 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
+import * as En from 'blockly/msg/en';
+import 'blockly/blocks';
 import {registerAllBlocks} from './blocks';
 import {toolbox} from './toolbox';
 import './index.css';
@@ -14,6 +16,9 @@ import {load, save} from './serialization';
 // Put Blockly in the global scope for easy debugging.
 (window as any).Blockly = Blockly;
 
+// Even though En should be loaded by default,
+// if you don't load it specifically, you'll get spurious message warnings.
+Blockly.setLocale(En);
 registerAllBlocks();
 
 const mainWorkspaceDiv = document.getElementById('mainWorkspace');
diff --git a/examples/developer-tools/src/output-generators/colour.ts b/examples/developer-tools/src/output-generators/colour.ts
index ead3997ca2..70d811b638 100644
--- a/examples/developer-tools/src/output-generators/colour.ts
+++ b/examples/developer-tools/src/output-generators/colour.ts
@@ -9,7 +9,7 @@ import {
   Order,
   jsonDefinitionGenerator,
 } from './json_definition_generator';
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * JSON definition for the "input" block.
diff --git a/examples/developer-tools/src/output-generators/factory_base.ts b/examples/developer-tools/src/output-generators/factory_base.ts
index 85eb2ce4bf..a4d10164bc 100644
--- a/examples/developer-tools/src/output-generators/factory_base.ts
+++ b/examples/developer-tools/src/output-generators/factory_base.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {javascriptGenerator} from 'blockly/javascript';
 import {
   JsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/checkbox.ts b/examples/developer-tools/src/output-generators/fields/checkbox.ts
index 4b03934dcb..2642f603d1 100644
--- a/examples/developer-tools/src/output-generators/fields/checkbox.ts
+++ b/examples/developer-tools/src/output-generators/fields/checkbox.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/image.ts b/examples/developer-tools/src/output-generators/fields/image.ts
index 543314877e..2dfec11540 100644
--- a/examples/developer-tools/src/output-generators/fields/image.ts
+++ b/examples/developer-tools/src/output-generators/fields/image.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/label.ts b/examples/developer-tools/src/output-generators/fields/label.ts
index 81e6ed0a0e..20c3ef6bbb 100644
--- a/examples/developer-tools/src/output-generators/fields/label.ts
+++ b/examples/developer-tools/src/output-generators/fields/label.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/label_serializable.ts b/examples/developer-tools/src/output-generators/fields/label_serializable.ts
index 31f11d56ce..df0eace46c 100644
--- a/examples/developer-tools/src/output-generators/fields/label_serializable.ts
+++ b/examples/developer-tools/src/output-generators/fields/label_serializable.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/number.ts b/examples/developer-tools/src/output-generators/fields/number.ts
index d27d9b71ae..4ff90b6928 100644
--- a/examples/developer-tools/src/output-generators/fields/number.ts
+++ b/examples/developer-tools/src/output-generators/fields/number.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/text_input.ts b/examples/developer-tools/src/output-generators/fields/text_input.ts
index d65ddf284b..e46ed8e1d2 100644
--- a/examples/developer-tools/src/output-generators/fields/text_input.ts
+++ b/examples/developer-tools/src/output-generators/fields/text_input.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/fields/variable.ts b/examples/developer-tools/src/output-generators/fields/variable.ts
index 230d2500ce..0322e0f295 100644
--- a/examples/developer-tools/src/output-generators/fields/variable.ts
+++ b/examples/developer-tools/src/output-generators/fields/variable.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   jsonDefinitionGenerator,
diff --git a/examples/developer-tools/src/output-generators/input.ts b/examples/developer-tools/src/output-generators/input.ts
index 0b7b78d52e..33bc91882a 100644
--- a/examples/developer-tools/src/output-generators/input.ts
+++ b/examples/developer-tools/src/output-generators/input.ts
@@ -9,7 +9,7 @@ import {
   Order,
   jsonDefinitionGenerator,
 } from './json_definition_generator';
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * JSON definition for the "input" block.
diff --git a/examples/developer-tools/src/output-generators/json_definition_generator.ts b/examples/developer-tools/src/output-generators/json_definition_generator.ts
index 1f3d0b4308..e1a6e34ec7 100644
--- a/examples/developer-tools/src/output-generators/json_definition_generator.ts
+++ b/examples/developer-tools/src/output-generators/json_definition_generator.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 
 /**
  * We will never need parentheses for the JSON definition, so
diff --git a/examples/developer-tools/src/output-generators/type.ts b/examples/developer-tools/src/output-generators/type.ts
index ebb74734d5..50205c503a 100644
--- a/examples/developer-tools/src/output-generators/type.ts
+++ b/examples/developer-tools/src/output-generators/type.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import * as Blockly from 'blockly';
+import * as Blockly from 'blockly/core';
 import {
   JsonDefinitionGenerator,
   Order,