diff --git a/mocha.opts b/mocha.opts
index 14409727d..ff9c0b5dc 100644
--- a/mocha.opts
+++ b/mocha.opts
@@ -1,5 +1,4 @@
 --require source-map-support/register
 --require sucrase/register
 --recursive
-test/unit/*/test.ts
-test/apps/*/test.ts
+test/**/*test.ts
diff --git a/src/core/create_compilers/RollupResult.ts b/src/core/create_compilers/RollupResult.ts
index 99ea2a51f..41d88f095 100644
--- a/src/core/create_compilers/RollupResult.ts
+++ b/src/core/create_compilers/RollupResult.ts
@@ -3,7 +3,7 @@ import colors from 'kleur';
 import pb from 'pretty-bytes';
 import RollupCompiler from './RollupCompiler';
 import extract_css from './extract_css';
-import { left_pad } from '../../utils';
+import { left_pad, normalize_path } from '../../utils';
 import { CompileResult, BuildInfo, CompileError, Chunk, CssFile } from './interfaces';
 import { ManifestData, Dirs } from '../../interfaces';
 
@@ -31,7 +31,7 @@ export default class RollupResult implements CompileResult {
 		this.chunks = compiler.chunks.map(chunk => ({
 			file: chunk.fileName,
 			imports: chunk.imports.filter(Boolean),
-			modules: Object.keys(chunk.modules)
+			modules: Object.keys(chunk.modules).map(m => normalize_path(m))
 		}));
 
 		this.css_files = compiler.css_files;
diff --git a/src/core/create_compilers/extract_css.ts b/src/core/create_compilers/extract_css.ts
index d2a22959c..71452378f 100644
--- a/src/core/create_compilers/extract_css.ts
+++ b/src/core/create_compilers/extract_css.ts
@@ -4,7 +4,7 @@ import hash from 'string-hash';
 import * as codec from 'sourcemap-codec';
 import { PageComponent, Dirs } from '../../interfaces';
 import { CompileResult, Chunk } from './interfaces';
-import { posixify } from '../../utils'
+import { normalize_path, posixify } from '../../utils'
 
 const inline_sourcemap_header = 'data:application/json;charset=utf-8;base64,';
 
@@ -192,13 +192,12 @@ export default function extract_css(
 
 	// figure out which (css-having) chunks each component depends on
 	components.forEach(component => {
-		const resolved = path.resolve(dirs.routes, component.file);
+		const resolved = normalize_path(path.resolve(dirs.routes, component.file));
 		const chunk: Chunk = client_result.chunks.find(chunk => chunk.modules.indexOf(resolved) !== -1);
 
 		if (!chunk) {
 			// this should never happen!
-			return;
-			// throw new Error(`Could not find chunk that owns ${component.file}`);
+			throw new Error(`Could not find chunk that owns ${component.file}`);
 		}
 
 		const chunk_dependencies: Set<Chunk> = new Set([chunk]);
diff --git a/src/utils.ts b/src/utils.ts
index 43bbad689..82afcd3eb 100644
--- a/src/utils.ts
+++ b/src/utils.ts
@@ -116,4 +116,10 @@ export const reserved_words = new Set([
 	'while',
 	'with',
 	'yield',
-]);
\ No newline at end of file
+]);
+
+export function normalize_path(user_path) {
+	const p = path.normalize(user_path);
+	// normalize drive letter on Windows
+	return p.length ? p.charAt(0).toLowerCase() + p.slice(1) : '';
+}
diff --git a/test/unit/utils.test.ts b/test/unit/utils.test.ts
new file mode 100644
index 000000000..01551844f
--- /dev/null
+++ b/test/unit/utils.test.ts
@@ -0,0 +1,9 @@
+import * as assert from 'assert';
+import { normalize_path } from '../../src/utils';
+
+describe('normalize_path', () => {
+	it('lowercases the first letter', () => {
+		assert.equal(normalize_path('C:\\Users\\simon\\Source\\my-app\\src\\routes\\index.svelte'),
+			'c:\\Users\\simon\\Source\\my-app\\src\\routes\\index.svelte');
+	});
+});