diff --git a/src/tree/__tests__/populateTree.spec.ts b/src/tree/__tests__/populateTree.spec.ts
index 61ce88c6..9bd3664d 100644
--- a/src/tree/__tests__/populateTree.spec.ts
+++ b/src/tree/__tests__/populateTree.spec.ts
@@ -1,7 +1,9 @@
-import { Tree } from '@stoplight/tree-list';
+import { Tree, TreeListParentNode } from '@stoplight/tree-list';
 import * as fs from 'fs';
+import { JSONSchema4 } from 'json-schema';
 import * as path from 'path';
 import { generateId } from '../../utils/generateId';
+import { getNodeMetadata } from '../metadata';
 import { populateTree } from '../utils/populateTree';
 
 const BASE_PATH = path.resolve(__dirname, '../../__fixtures__/');
@@ -47,9 +49,9 @@ describe('populateTree util', () => {
   });
 
   it('given schema with complex types, throws', () => {
-    const schema = {
+    const schema: JSONSchema4 = {
       type: [
-        'null',
+        'null' as any,
         {
           type: 'object',
           properties: {
@@ -63,8 +65,25 @@ describe('populateTree util', () => {
     };
 
     const root = Tree.createArtificialRoot();
-    expect(() => populateTree(schema as any, root, 0, [], null)).toThrow(
+    expect(() => populateTree(schema, root, 0, [], null)).toThrow(
       'The "type" property must be a string, or an array of strings. Objects and array of objects are not valid.',
     );
   });
+
+  it('includes properties with unknown types', () => {
+    const schema: JSONSchema4 = {
+      type: 'object',
+      properties: {
+        foo: {
+          __ERROR__: 'dd',
+        },
+      },
+    };
+
+    const root = Tree.createArtificialRoot();
+    populateTree(schema, root, 0, [], null);
+    expect(getNodeMetadata((root.children[0] as TreeListParentNode).children[0])).toHaveProperty('schema', {
+      __ERROR__: 'dd',
+    });
+  });
 });
diff --git a/src/tree/utils/walk.ts b/src/tree/utils/walk.ts
index c8599dfd..0f369601 100644
--- a/src/tree/utils/walk.ts
+++ b/src/tree/utils/walk.ts
@@ -72,6 +72,12 @@ function processNode(node: JSONSchema4): SchemaNode | void {
   // if ('not' in node) {
   //   // todo: shall we support it?
   // }
+
+  return {
+    id: generateId(),
+    validations: {},
+    annotations: {},
+  };
 }
 
 export type WalkerValue = {
diff --git a/src/types.ts b/src/types.ts
index 2424e6e6..37d26831 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -31,7 +31,7 @@ export interface ICombinerNode {
 export interface IBaseNode extends Pick<JSONSchema4, 'enum'> {
   id: string;
   readonly type?: JSONSchema4TypeName | JSONSchema4TypeName[];
-  annotations: Pick<JSONSchema4, JSONSchema4Annotations>;
+  annotations: Partial<Pick<JSONSchema4, JSONSchema4Annotations>>;
   validations: Dictionary<unknown>;
   required?: string[];
 }