diff --git a/packages/compiler-cli/src/ngtsc/shims/src/factory_generator.ts b/packages/compiler-cli/src/ngtsc/shims/src/factory_generator.ts
index 90829bbaac..d8b94c4e54 100644
--- a/packages/compiler-cli/src/ngtsc/shims/src/factory_generator.ts
+++ b/packages/compiler-cli/src/ngtsc/shims/src/factory_generator.ts
@@ -9,7 +9,7 @@
 import * as path from 'path';
 import * as ts from 'typescript';
 
-import {relativePathBetween} from '../../util/src/path';
+import {normalizeSeparators, relativePathBetween} from '../../util/src/path';
 
 import {ShimGenerator} from './host';
 import {generatedModuleName, isNonDeclarationTsFile} from './util';
@@ -88,6 +88,7 @@ export class FactoryGenerator implements ShimGenerator {
   static forRootFiles(files: ReadonlyArray<string>): FactoryGenerator {
     const map = new Map<string, string>();
     files.filter(sourceFile => isNonDeclarationTsFile(sourceFile))
+        .map(sourceFile => normalizeSeparators(sourceFile))
         .forEach(sourceFile => map.set(sourceFile.replace(/\.ts$/, '.ngfactory.ts'), sourceFile));
     return new FactoryGenerator(map);
   }
diff --git a/packages/compiler-cli/src/ngtsc/shims/src/summary_generator.ts b/packages/compiler-cli/src/ngtsc/shims/src/summary_generator.ts
index 158f0fdba6..5fa103f940 100644
--- a/packages/compiler-cli/src/ngtsc/shims/src/summary_generator.ts
+++ b/packages/compiler-cli/src/ngtsc/shims/src/summary_generator.ts
@@ -8,6 +8,8 @@
 
 import * as ts from 'typescript';
 
+import {normalizeSeparators} from '../../util/src/path';
+
 import {ShimGenerator} from './host';
 import {generatedModuleName, isNonDeclarationTsFile} from './util';
 
@@ -62,6 +64,7 @@ export class SummaryGenerator implements ShimGenerator {
   static forRootFiles(files: ReadonlyArray<string>): SummaryGenerator {
     const map = new Map<string, string>();
     files.filter(sourceFile => isNonDeclarationTsFile(sourceFile))
+        .map(sourceFile => normalizeSeparators(sourceFile))
         .forEach(sourceFile => map.set(sourceFile.replace(/\.ts$/, '.ngsummary.ts'), sourceFile));
     return new SummaryGenerator(map);
   }
diff --git a/packages/compiler-cli/src/ngtsc/util/src/path.ts b/packages/compiler-cli/src/ngtsc/util/src/path.ts
index 4c5d11c55f..fc8300f017 100644
--- a/packages/compiler-cli/src/ngtsc/util/src/path.ts
+++ b/packages/compiler-cli/src/ngtsc/util/src/path.ts
@@ -26,3 +26,8 @@ export function relativePathBetween(from: string, to: string): string|null {
 
   return relative;
 }
+
+export function normalizeSeparators(path: string): string {
+  // TODO: normalize path only for OS that need it.
+  return path.replace(/\\/g, '/');
+}