diff --git a/etc/api/angular_devkit/core/src/_golden-api.d.ts b/etc/api/angular_devkit/core/src/_golden-api.d.ts
index e07a427eb66f..7dab611a0ced 100644
--- a/etc/api/angular_devkit/core/src/_golden-api.d.ts
+++ b/etc/api/angular_devkit/core/src/_golden-api.d.ts
@@ -5,7 +5,7 @@ export interface AdditionalPropertiesValidatorError extends SchemaValidatorError
     };
 }
 
-export declare function addUndefinedDefaults(value: JsonValue, _pointer: JsonPointer, schema?: JsonObject): JsonValue;
+export declare function addUndefinedDefaults(value: JsonValue, _pointer: JsonPointer, schema?: JsonSchema): JsonValue;
 
 export declare class AliasHost<StatsT extends object = {}> extends ResolverHost<StatsT> {
     protected _aliases: Map<Path, Path>;
@@ -989,7 +989,7 @@ export declare class UnsupportedPlatformException extends BaseException {
 
 export declare type UriHandler = (uri: string) => Observable<JsonObject> | Promise<JsonObject> | null | undefined;
 
-export declare function visitJson<ContextT>(json: JsonValue, visitor: JsonVisitor, schema?: JsonObject, refResolver?: ReferenceResolver<ContextT>, context?: ContextT): Observable<JsonValue>;
+export declare function visitJson<ContextT>(json: JsonValue, visitor: JsonVisitor, schema?: JsonSchema, refResolver?: ReferenceResolver<ContextT>, context?: ContextT): Observable<JsonValue>;
 
 export declare function visitJsonSchema(schema: JsonSchema, visitor: JsonSchemaVisitor): void;
 
diff --git a/packages/angular_devkit/core/src/json/schema/registry.ts b/packages/angular_devkit/core/src/json/schema/registry.ts
index aa98bac3e18c..b04bbc8c7b82 100644
--- a/packages/angular_devkit/core/src/json/schema/registry.ts
+++ b/packages/angular_devkit/core/src/json/schema/registry.ts
@@ -347,10 +347,6 @@ export class CoreSchemaRegistry implements SchemaRegistry {
             // tslint:disable-next-line:no-any https://github.com/ReactiveX/rxjs/issues/3989
             result = (result as any).pipe(
               ...[...this._pre].map(visitor => concatMap((data: JsonValue) => {
-                if (schema === false || schema === true) {
-                  return of(data);
-                }
-
                 return visitJson(data, visitor, schema, this._resolver, validate);
               })),
             );
@@ -418,10 +414,6 @@ export class CoreSchemaRegistry implements SchemaRegistry {
                   // tslint:disable-next-line:no-any https://github.com/ReactiveX/rxjs/issues/3989
                   result = (result as any).pipe(
                     ...[...this._post].map(visitor => concatMap((data: JsonValue) => {
-                      if (schema === false || schema === true) {
-                        return of(schema);
-                      }
-
                       return visitJson(data, visitor, schema, this._resolver, validate);
                     })),
                   );
diff --git a/packages/angular_devkit/core/src/json/schema/registry_spec.ts b/packages/angular_devkit/core/src/json/schema/registry_spec.ts
index fa512977605f..337e82e719df 100644
--- a/packages/angular_devkit/core/src/json/schema/registry_spec.ts
+++ b/packages/angular_devkit/core/src/json/schema/registry_spec.ts
@@ -382,6 +382,18 @@ describe('CoreSchemaRegistry', () => {
       .toPromise().then(done, done.fail);
   });
 
+  it('works with true as a schema and post-transforms', async () => {
+    const registry = new CoreSchemaRegistry();
+    registry.addPostTransform(addUndefinedDefaults);
+    const data: any = { a: 1, b: 2 };  // tslint:disable-line:no-any
+
+    const validate = await registry.compile(true).toPromise();
+    const result = await validate(data).toPromise();
+
+    expect(result.success).toBe(true);
+    expect(result.data).toBe(data);
+  });
+
   it('adds undefined properties', done => {
     const registry = new CoreSchemaRegistry();
     registry.addPostTransform(addUndefinedDefaults);
diff --git a/packages/angular_devkit/core/src/json/schema/transforms.ts b/packages/angular_devkit/core/src/json/schema/transforms.ts
index 9c6694e4e32e..e047d3c38f2a 100644
--- a/packages/angular_devkit/core/src/json/schema/transforms.ts
+++ b/packages/angular_devkit/core/src/json/schema/transforms.ts
@@ -7,14 +7,18 @@
  */
 import { JsonObject, JsonValue, isJsonObject } from '../interface';
 import { JsonPointer } from './interface';
+import { JsonSchema } from './schema';
 import { getTypesOfSchema } from './utility';
 
 export function addUndefinedDefaults(
   value: JsonValue,
   _pointer: JsonPointer,
-  schema?: JsonObject,
+  schema?: JsonSchema,
 ): JsonValue {
-  if (!schema) {
+  if (schema === true || schema === false) {
+    return value;
+  }
+  if (schema === undefined) {
     return value;
   }
 
diff --git a/packages/angular_devkit/core/src/json/schema/visitor.ts b/packages/angular_devkit/core/src/json/schema/visitor.ts
index 130ef4925846..b3b46c40df9f 100644
--- a/packages/angular_devkit/core/src/json/schema/visitor.ts
+++ b/packages/angular_devkit/core/src/json/schema/visitor.ts
@@ -19,7 +19,7 @@ export interface ReferenceResolver<ContextT> {
 }
 
 function _getObjectSubSchema(
-  schema: JsonObject | undefined,
+  schema: JsonSchema | undefined,
   key: string,
 ): JsonObject | undefined {
   if (typeof schema !== 'object' || schema === null) {
@@ -51,11 +51,15 @@ function _visitJsonRecursive<ContextT>(
   json: JsonValue,
   visitor: JsonVisitor,
   ptr: JsonPointer,
-  schema?: JsonObject,
+  schema?: JsonSchema,
   refResolver?: ReferenceResolver<ContextT>,
   context?: ContextT,  // tslint:disable-line:no-any
   root?: JsonObject | JsonArray,
 ): Observable<JsonValue> {
+  if (schema === true || schema === false) {
+    // There's no schema definition, so just visit the JSON recursively.
+    schema = undefined;
+  }
   if (schema && schema.hasOwnProperty('$ref') && typeof schema['$ref'] == 'string') {
     if (refResolver) {
       const resolved = refResolver(schema['$ref'] as string, context);
@@ -132,7 +136,7 @@ function _visitJsonRecursive<ContextT>(
 export function visitJson<ContextT>(
   json: JsonValue,
   visitor: JsonVisitor,
-  schema?: JsonObject,
+  schema?: JsonSchema,
   refResolver?: ReferenceResolver<ContextT>,
   context?: ContextT,  // tslint:disable-line:no-any
 ): Observable<JsonValue> {