diff --git a/packages/compiler-cli/ngcc/src/dependencies/module_resolver.ts b/packages/compiler-cli/ngcc/src/dependencies/module_resolver.ts
index e8c12e361d..c558a2bb97 100644
--- a/packages/compiler-cli/ngcc/src/dependencies/module_resolver.ts
+++ b/packages/compiler-cli/ngcc/src/dependencies/module_resolver.ts
@@ -118,7 +118,7 @@ export class ModuleResolver {
    */
   private resolveAsEntryPoint(moduleName: string, fromPath: AbsoluteFsPath): ResolvedModule|null {
     let folder = fromPath;
-    while (folder !== '/') {
+    while (!AbsoluteFsPath.isRoot(folder)) {
       folder = AbsoluteFsPath.dirname(folder);
       if (folder.endsWith('node_modules')) {
         // Skip up if the folder already ends in node_modules
@@ -225,7 +225,7 @@ export class ModuleResolver {
    */
   private findPackagePath(path: AbsoluteFsPath): AbsoluteFsPath|null {
     let folder = path;
-    while (folder !== '/') {
+    while (!AbsoluteFsPath.isRoot(folder)) {
       folder = AbsoluteFsPath.dirname(folder);
       if (this.fs.exists(AbsoluteFsPath.join(folder, 'package.json'))) {
         return folder;
diff --git a/packages/compiler-cli/ngcc/src/packages/ngcc_compiler_host.ts b/packages/compiler-cli/ngcc/src/packages/ngcc_compiler_host.ts
index 19ddb626dd..d437a51945 100644
--- a/packages/compiler-cli/ngcc/src/packages/ngcc_compiler_host.ts
+++ b/packages/compiler-cli/ngcc/src/packages/ngcc_compiler_host.ts
@@ -27,7 +27,7 @@ export class NgccCompilerHost implements ts.CompilerHost {
   }
 
   getDefaultLibLocation(): string {
-    const nodeLibPath = AbsoluteFsPath.fromUnchecked(require.resolve('typescript'));
+    const nodeLibPath = AbsoluteFsPath.from(require.resolve('typescript'));
     return AbsoluteFsPath.join(nodeLibPath, '..');
   }
 
diff --git a/packages/compiler-cli/ngcc/test/helpers/mock_file_system.ts b/packages/compiler-cli/ngcc/test/helpers/mock_file_system.ts
index c47e2f359e..3e8fd219b4 100644
--- a/packages/compiler-cli/ngcc/test/helpers/mock_file_system.ts
+++ b/packages/compiler-cli/ngcc/test/helpers/mock_file_system.ts
@@ -14,7 +14,7 @@ import {FileStats, FileSystem} from '../../src/file_system/file_system';
 export class MockFileSystem implements FileSystem {
   files: Folder = {};
   constructor(...folders: Folder[]) {
-    folders.forEach(files => this.processFiles(this.files, files));
+    folders.forEach(files => this.processFiles(this.files, files, true));
   }
 
   exists(path: AbsoluteFsPath): boolean { return this.findFromPath(path) !== null; }
@@ -67,7 +67,7 @@ export class MockFileSystem implements FileSystem {
     return new MockFileStats(fileOrFolder);
   }
 
-  pwd(): AbsoluteFsPath { return AbsoluteFsPath.fromUnchecked('/'); }
+  pwd(): AbsoluteFsPath { return AbsoluteFsPath.from('/'); }
 
   copyFile(from: AbsoluteFsPath, to: AbsoluteFsPath): void {
     this.writeFile(to, this.readFile(from));
@@ -82,9 +82,10 @@ export class MockFileSystem implements FileSystem {
 
   ensureDir(path: AbsoluteFsPath): void { this.ensureFolders(this.files, path.split('/')); }
 
-  private processFiles(current: Folder, files: Folder): void {
+  private processFiles(current: Folder, files: Folder, isRootPath = false): void {
     Object.keys(files).forEach(path => {
-      const segments = path.split('/');
+      const pathResolved = isRootPath ? AbsoluteFsPath.from(path) : path;
+      const segments = pathResolved.split('/');
       const lastSegment = segments.pop() !;
       const containingFolder = this.ensureFolders(current, segments);
       const entity = files[path];
diff --git a/packages/compiler-cli/src/ngtsc/path/src/types.ts b/packages/compiler-cli/src/ngtsc/path/src/types.ts
index 6561d7e2fe..7286aeaaa7 100644
--- a/packages/compiler-cli/src/ngtsc/path/src/types.ts
+++ b/packages/compiler-cli/src/ngtsc/path/src/types.ts
@@ -40,6 +40,12 @@ export const AbsoluteFsPath = {
    * Convert the path `str` to an `AbsoluteFsPath`, throwing an error if it's not an absolute path.
    */
   from: function(str: string): AbsoluteFsPath {
+    if (str.startsWith('/') && process.platform === 'win32') {
+      // in Windows if it's absolute path and starts with `/` we shall
+      // resolve it and return it including the drive.
+      str = path.resolve(str);
+    }
+
     const normalized = normalizeSeparators(str);
     if (!isAbsolutePath(normalized)) {
       throw new Error(`Internal Error: AbsoluteFsPath.from(${str}): path is not absolute`);
@@ -80,6 +86,9 @@ export const AbsoluteFsPath = {
    */
   resolve: function(basePath: string, ...paths: string[]):
       AbsoluteFsPath { return AbsoluteFsPath.from(path.resolve(basePath, ...paths));},
+
+  /** Returns true when the path provided is the root path. */
+  isRoot: function(path: AbsoluteFsPath): boolean { return AbsoluteFsPath.dirname(path) === path;},
 };
 
 /**