diff --git a/packages/core/schematics/test/project_tsconfig_paths_spec.ts b/packages/core/schematics/test/project_tsconfig_paths_spec.ts
index b26137eb37..31cc793ae7 100644
--- a/packages/core/schematics/test/project_tsconfig_paths_spec.ts
+++ b/packages/core/schematics/test/project_tsconfig_paths_spec.ts
@@ -22,7 +22,7 @@ describe('project tsconfig paths', () => {
           {my_name: {architect: {build: {options: {tsConfig: './my-custom-config.json'}}}}}
     }));
 
-    expect(getProjectTsConfigPaths(testTree)).toEqual(['./my-custom-config.json']);
+    expect(getProjectTsConfigPaths(testTree)).toEqual(['my-custom-config.json']);
   });
 
   it('should detect test tsconfig path inside of .angular.json file', () => {
@@ -32,7 +32,7 @@ describe('project tsconfig paths', () => {
           {with_tests: {architect: {test: {options: {tsConfig: './my-test-config.json'}}}}}
     }));
 
-    expect(getProjectTsConfigPaths(testTree)).toEqual(['./my-test-config.json']);
+    expect(getProjectTsConfigPaths(testTree)).toEqual(['my-test-config.json']);
   });
 
   it('should detect common tsconfigs if no workspace config could be found', () => {
@@ -41,7 +41,16 @@ describe('project tsconfig paths', () => {
     testTree.create('/src/tsconfig.app.json', '');
 
     expect(getProjectTsConfigPaths(testTree)).toEqual([
-      './tsconfig.json', './src/tsconfig.json', './src/tsconfig.app.json'
+      'tsconfig.json', 'src/tsconfig.json', 'src/tsconfig.app.json'
     ]);
   });
+
+  it('should not return duplicate tsconfig files', () => {
+    testTree.create('/tsconfig.json', '');
+    testTree.create('/.angular.json', JSON.stringify({
+      projects: {app: {architect: {test: {options: {tsConfig: 'tsconfig.json'}}}}}
+    }));
+
+    expect(getProjectTsConfigPaths(testTree)).toEqual(['tsconfig.json']);
+  });
 });
diff --git a/packages/core/schematics/utils/BUILD.bazel b/packages/core/schematics/utils/BUILD.bazel
index cffc353f4d..df0004600e 100644
--- a/packages/core/schematics/utils/BUILD.bazel
+++ b/packages/core/schematics/utils/BUILD.bazel
@@ -8,5 +8,8 @@ ts_library(
     ),
     tsconfig = "//packages/core/schematics:tsconfig.json",
     visibility = ["//packages/core/schematics:__subpackages__"],
-    deps = ["@npm//@angular-devkit/schematics"],
+    deps = [
+        "@npm//@angular-devkit/core",
+        "@npm//@angular-devkit/schematics",
+    ],
 )
diff --git a/packages/core/schematics/utils/project_tsconfig_paths.ts b/packages/core/schematics/utils/project_tsconfig_paths.ts
index 4623f012af..a6ef3219c7 100644
--- a/packages/core/schematics/utils/project_tsconfig_paths.ts
+++ b/packages/core/schematics/utils/project_tsconfig_paths.ts
@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import {normalize} from '@angular-devkit/core';
 import {Tree} from '@angular-devkit/schematics';
 
 /** Name of the default Angular CLI workspace configuration files. */
@@ -18,9 +19,9 @@ const defaultWorkspaceConfigPaths = ['/angular.json', '/.angular.json'];
 export function getProjectTsConfigPaths(tree: Tree): string[] {
   // Start with some tsconfig paths that are generally used within CLI projects.
   const tsconfigPaths = new Set<string>([
-    './tsconfig.json',
-    './src/tsconfig.json',
-    './src/tsconfig.app.json',
+    'tsconfig.json',
+    'src/tsconfig.json',
+    'src/tsconfig.app.json',
   ]);
 
   // Add any tsconfig directly referenced in a build or test task of the angular.json workspace.
@@ -32,13 +33,13 @@ export function getProjectTsConfigPaths(tree: Tree): string[] {
       ['build', 'test'].forEach(targetName => {
         if (project.targets && project.targets[targetName] && project.targets[targetName].options &&
             project.targets[targetName].options.tsConfig) {
-          tsconfigPaths.add(project.targets[targetName].options.tsConfig);
+          tsconfigPaths.add(normalize(project.targets[targetName].options.tsConfig));
         }
 
         if (project.architect && project.architect[targetName] &&
             project.architect[targetName].options &&
             project.architect[targetName].options.tsConfig) {
-          tsconfigPaths.add(project.architect[targetName].options.tsConfig);
+          tsconfigPaths.add(normalize(project.architect[targetName].options.tsConfig));
         }
       });
     }