diff --git a/libs/interpreter-lib/src/parsing-util.spec.ts b/libs/interpreter-lib/src/parsing-util.spec.ts
index 58e7dcf68..cd5de83db 100644
--- a/libs/interpreter-lib/src/parsing-util.spec.ts
+++ b/libs/interpreter-lib/src/parsing-util.spec.ts
@@ -8,11 +8,10 @@ import { CachedLogger } from '@jvalue/jayvee-execution';
 import {
   JayveeServices,
   createJayveeServices,
-  useExtension,
+  initializeWorkspace,
 } from '@jvalue/jayvee-language-server';
 import {
   ParseHelperOptions,
-  TestLangExtension,
   expectNoParserAndLexerErrors,
   parseHelper,
   readJvTestAssetHelper,
@@ -39,7 +38,7 @@ describe('Validation of parsing-util', () => {
     '../test/assets/parsing-util/',
   );
 
-  beforeAll(() => {
+  beforeAll(async () => {
     // Mock Process.exit
     exitSpy = jest
       .spyOn(process, 'exit')
@@ -50,10 +49,16 @@ describe('Validation of parsing-util', () => {
         throw new Error(`process.exit: ${code}`);
       });
 
-    // Register test extension
-    useExtension(new TestLangExtension());
     // Create language services
     services = createJayveeServices(NodeFileSystem).Jayvee;
+
+    await initializeWorkspace(services, [
+      {
+        uri: process.cwd(),
+        name: 'TestBlockTypes.jv',
+      },
+    ]);
+
     // Parse function for Jayvee (without validation)
     parse = parseHelper(services);
   });
diff --git a/libs/interpreter-lib/src/validation-checks/runtime-parameter-literal.spec.ts b/libs/interpreter-lib/src/validation-checks/runtime-parameter-literal.spec.ts
index 3475001a1..2e392e10f 100644
--- a/libs/interpreter-lib/src/validation-checks/runtime-parameter-literal.spec.ts
+++ b/libs/interpreter-lib/src/validation-checks/runtime-parameter-literal.spec.ts
@@ -9,11 +9,10 @@ import {
   RuntimeParameterProvider,
   ValidationContext,
   createJayveeServices,
-  useExtension,
+  initializeWorkspace,
 } from '@jvalue/jayvee-language-server';
 import {
   ParseHelperOptions,
-  TestLangExtension,
   expectNoParserAndLexerErrors,
   parseHelper,
   readJvTestAssetHelper,
@@ -66,12 +65,18 @@ describe('Validation of validateRuntimeParameterLiteral', () => {
     );
   }
 
-  beforeAll(() => {
-    // Register test extension
-    useExtension(new TestLangExtension());
+  beforeAll(async () => {
     // Create language services
     const services = createJayveeServices(NodeFileSystem).Jayvee;
+
+    await initializeWorkspace(services, [
+      {
+        uri: process.cwd(),
+        name: 'TestBlockTypes.jv',
+      },
+    ]);
     locator = services.workspace.AstNodeLocator;
+
     // Parse function for Jayvee (without validation)
     parse = parseHelper(services);
   });
diff --git a/libs/interpreter-lib/test/assets/parsing-util/test-extension/TestBlockTypes.jv b/libs/interpreter-lib/test/assets/parsing-util/test-extension/TestBlockTypes.jv
new file mode 100644
index 000000000..99437d387
--- /dev/null
+++ b/libs/interpreter-lib/test/assets/parsing-util/test-extension/TestBlockTypes.jv
@@ -0,0 +1,14 @@
+builtin blocktype TestFileExtractor {
+    input inPort oftype None;
+    output outPort oftype File;
+}
+
+builtin blocktype TestFileLoader {
+    input inPort oftype File;
+    output outPort oftype None;
+}
+
+builtin blocktype TestTableLoader {
+    input inPort oftype Table;
+    output outPort oftype None;
+}
diff --git a/libs/language-server/src/lib/builtin-library/jayvee-workspace-manager.ts b/libs/language-server/src/lib/builtin-library/jayvee-workspace-manager.ts
index 88f43e3a3..5c93277c7 100644
--- a/libs/language-server/src/lib/builtin-library/jayvee-workspace-manager.ts
+++ b/libs/language-server/src/lib/builtin-library/jayvee-workspace-manager.ts
@@ -40,8 +40,8 @@ export class JayveeWorkspaceManager extends DefaultWorkspaceManager {
  */
 export async function initializeWorkspace(
   services: LangiumServices,
+  workspaceFolders: WorkspaceFolder[] = [],
 ): Promise<void> {
-  const workspaceFolders: WorkspaceFolder[] = [];
   await services.shared.workspace.WorkspaceManager.initializeWorkspace(
     workspaceFolders,
   );