diff --git a/shared/src/document-loader/calmhub-document-loader.spec.ts b/shared/src/document-loader/calmhub-document-loader.spec.ts
index 8564a2e07..98a0ce853 100644
--- a/shared/src/document-loader/calmhub-document-loader.spec.ts
+++ b/shared/src/document-loader/calmhub-document-loader.spec.ts
@@ -1,25 +1,28 @@
 import axios from 'axios';
 import AxiosMockAdapter from 'axios-mock-adapter';
 import { CalmHubDocumentLoader } from './calmhub-document-loader';
+import { SchemaDirectory } from '../schema-directory';
 
 const calmHubBaseUrl = 'http://local-calmhub';
 
 const ax = axios.create({ baseURL: calmHubBaseUrl });
 const mock = new AxiosMockAdapter(ax);
 
-mock.onGet('/calm/schemas/2025-03/meta/core.json').reply(200, {
+mock.onGet('/schemas/2025-03/meta/core.json').reply(200, {
     '$id': 'https://calm.finos.org/calm/schemas/2025-03/meta/core.json',
     'value': 'test'
 });
 
 describe('calmhub-document-loader', () => {
-    let calmHubDocumentLoader;
+    let calmHubDocumentLoader: CalmHubDocumentLoader;
+    let schemaDirectory: SchemaDirectory;
     beforeEach(() => {
         calmHubDocumentLoader = new CalmHubDocumentLoader(calmHubBaseUrl, false, ax);
+        calmHubDocumentLoader.initialise(schemaDirectory);
     });
 
     it('loads a document from CalmHub', async () => {
-        const calmHubUrl = 'https://calm.finos.org/calm/schemas/2025-03/meta/core.json';
+        const calmHubUrl = 'calm:/schemas/2025-03/meta/core.json';
         const document = await calmHubDocumentLoader.loadMissingDocument(calmHubUrl, 'schema');
         expect(document).toEqual({
             '$id': 'https://calm.finos.org/calm/schemas/2025-03/meta/core.json',
@@ -28,7 +31,13 @@ describe('calmhub-document-loader', () => {
     });
 
     it('throws an error when the document is not found', async () => {
-        const calmHubUrl = 'https://calm.finos.org/calm/schemas/2025-03/meta/nonexistent.json';
+        const calmHubUrl = 'calm:/schemas/2025-03/meta/nonexistent.json';
+
+        await expect(calmHubDocumentLoader.loadMissingDocument(calmHubUrl, 'schema')).rejects.toThrow();
+    });
+
+    it('throws an error when the protocol is not calm:', async () => {
+        const calmHubUrl = 'https://not.calmhub.com/schemas/2025-03/meta/nonexistent.json';
 
         await expect(calmHubDocumentLoader.loadMissingDocument(calmHubUrl, 'schema')).rejects.toThrow();
     });
diff --git a/shared/src/document-loader/calmhub-document-loader.ts b/shared/src/document-loader/calmhub-document-loader.ts
index f4bd50e48..c0691b58e 100644
--- a/shared/src/document-loader/calmhub-document-loader.ts
+++ b/shared/src/document-loader/calmhub-document-loader.ts
@@ -1,6 +1,6 @@
 import axios, { Axios } from 'axios';
 import { SchemaDirectory } from '../schema-directory';
-import { CalmDocumentType, DocumentLoader } from './document-loader';
+import { CalmDocumentType, DocumentLoader, CALM_HUB_PROTO } from './document-loader';
 import { initLogger, Logger } from '../logger';
 
 export class CalmHubDocumentLoader implements DocumentLoader {
@@ -47,6 +47,10 @@ export class CalmHubDocumentLoader implements DocumentLoader {
 
     async loadMissingDocument(documentId: string, _: CalmDocumentType): Promise<object> {
         const url = new URL(documentId);
+        const protocol = url.protocol;
+        if (protocol !== CALM_HUB_PROTO) {
+            throw new Error(`CalmHubDocumentLoader only loads documents with protocol '${CALM_HUB_PROTO}'. (Requested: ${protocol})`);
+        }
         const path = url.pathname;
 
         this.logger.debug(`Loading CALM schema from ${this.calmHubUrl}${path}`);
diff --git a/shared/src/document-loader/document-loader.spec.ts b/shared/src/document-loader/document-loader.spec.ts
index bdc3a65fd..c5ce4171b 100644
--- a/shared/src/document-loader/document-loader.spec.ts
+++ b/shared/src/document-loader/document-loader.spec.ts
@@ -33,26 +33,24 @@ describe('DocumentLoader', () => {
         vi.resetModules();
     });
 
-    it('should create a FileSystemDocumentLoader when loadMode is "filesystem"', () => {
+    it('should create a FileSystemDocumentLoader', () => {
 
         const docLoaderOpts: DocumentLoaderOptions = {
-            loadMode: 'filesystem',
             schemaDirectoryPath: 'schemas'
         };
 
-        buildDocumentLoader(docLoaderOpts, false);
+        buildDocumentLoader(docLoaderOpts);
 
         expect(mocks.fsDocLoader).toHaveBeenCalledWith([CALM_META_SCHEMA_DIRECTORY, 'schemas'], false);
     });
 
-    it('should create a CalmHubDocumentLoader when loadMode is "calmhub"', () => {
+    it('should create a CalmHubDocumentLoader when calmHubUrl is defined in loader options', () => {
 
         const docLoaderOpts: DocumentLoaderOptions = {
-            loadMode: 'calmhub',
             calmHubUrl: 'https://example.com'
         };
 
-        buildDocumentLoader(docLoaderOpts, false);
+        buildDocumentLoader(docLoaderOpts);
 
         expect(mocks.calmHubDocLoader).toHaveBeenCalledWith('https://example.com', false);
     });
diff --git a/shared/src/document-loader/document-loader.ts b/shared/src/document-loader/document-loader.ts
index abb7206e0..2f11f167f 100644
--- a/shared/src/document-loader/document-loader.ts
+++ b/shared/src/document-loader/document-loader.ts
@@ -7,6 +7,8 @@ import { MultiStrategyDocumentLoader } from './multi-strategy-document-loader';
 
 export type CalmDocumentType = 'architecture' | 'pattern' | 'schema';
 
+export const CALM_HUB_PROTO = 'calm:';
+
 export interface DocumentLoader {
     initialise(schemaDirectory: SchemaDirectory): Promise<void>;
     loadMissingDocument(documentId: string, type: CalmDocumentType): Promise<object>;