diff --git a/.changeset/tidy-snakes-listen.md b/.changeset/tidy-snakes-listen.md
new file mode 100644
index 000000000..23415219e
--- /dev/null
+++ b/.changeset/tidy-snakes-listen.md
@@ -0,0 +1,5 @@
+---
+'@shopify/theme-check-node': patch
+---
+
+Fix cross-file LiquidDoc checks on Windows by normalising snippet paths before lookup.
diff --git a/packages/theme-check-node/src/index.spec.ts b/packages/theme-check-node/src/index.spec.ts
index 04883b333..c776faf2c 100644
--- a/packages/theme-check-node/src/index.spec.ts
+++ b/packages/theme-check-node/src/index.spec.ts
@@ -1,7 +1,9 @@
-import { afterEach, assert, beforeEach, describe, expect, it } from 'vitest';
-import { Config, SourceCodeType, getTheme, getThemeFilesPathPattern } from './index';
+import { afterEach, assert, beforeEach, describe, expect, it, vi } from 'vitest';
+import os from 'node:os';
+import path from 'node:path';
+import { Config, SourceCodeType, getTheme, getThemeFilesPathPattern, themeCheckRun } from './index';
 import { Workspace, makeTempWorkspace } from './test/test-helpers';
-import { pathToFileURL } from 'node:url';
+import { fileURLToPath, pathToFileURL } from 'node:url';
 
 describe('Unit: getTheme', () => {
   let workspace: Workspace;
@@ -49,3 +51,45 @@ describe('Unit: getThemeFilesPathPattern', () => {
     expect(normalizedGlob).to.equal(__dirname.replace(/\\/g, '/') + '/**/*.{liquid,json}');
   });
 });
+
+describe('Integration: themeCheckRun', () => {
+  it('reports cross-file LiquidDoc errors with Windows separators and spaces in the root path', async () => {
+    const workspace = await makeTempWorkspace(
+      {
+        locales: {
+          'en.default.json': '{}',
+        },
+        sections: {
+          'main.liquid': "{% render 'card' %}",
+        },
+        snippets: {
+          'card.liquid': `
+          {% doc %}
+            @param {string} title - The card title
+          {% enddoc %}
+        `,
+        },
+      },
+      path.join(os.tmpdir(), 'theme check.XXXXX'),
+    );
+    const originalRelative = path.relative;
+
+    const relativeSpy = vi.spyOn(path, 'relative').mockImplementation((from, to) => {
+      const relative = originalRelative(from, to);
+      if (typeof from === 'string' && from.startsWith('file:')) {
+        return relative.replace(/\//g, '\\');
+      }
+      return relative;
+    });
+
+    try {
+      const { offenses } = await themeCheckRun(fileURLToPath(workspace.rootUri));
+      expect(
+        offenses.filter(({ check }) => check === 'MissingRenderSnippetArguments'),
+      ).toHaveLength(1);
+    } finally {
+      relativeSpy.mockRestore();
+      await workspace.clean();
+    }
+  });
+});
diff --git a/packages/theme-check-node/src/index.ts b/packages/theme-check-node/src/index.ts
index 22cb13827..5dc08c1fb 100644
--- a/packages/theme-check-node/src/index.ts
+++ b/packages/theme-check-node/src/index.ts
@@ -125,7 +125,7 @@ export async function themeCheckRun(
   ]));
   const docDefinitions = new Map(
     theme.map((file) => [
-      path.relative(URI.file(root).toString(), file.uri),
+      pathUtils.relative(file.uri, pathUtils.normalize(URI.file(root))),
       memo(async (): Promise<DocDefinition | undefined> => {
         const ast = file.ast;
         if (!isLiquidHtmlNode(ast)) {
diff --git a/packages/theme-check-node/src/test/test-helpers.ts b/packages/theme-check-node/src/test/test-helpers.ts
index c55af1ec3..7efe8a7e3 100644
--- a/packages/theme-check-node/src/test/test-helpers.ts
+++ b/packages/theme-check-node/src/test/test-helpers.ts
@@ -74,8 +74,11 @@ export interface Workspace {
   clean(): Promise<any>;
 }
 
-export async function makeTempWorkspace(structure: Tree): Promise<Workspace> {
-  const root = await mktemp.createDir(path.join(__dirname, '..', '.XXXXX'));
+export async function makeTempWorkspace(
+  structure: Tree,
+  rootTemplate = path.join(__dirname, '..', '.XXXXX'),
+): Promise<Workspace> {
+  const root = await mktemp.createDir(rootTemplate);
   if (!root) throw new Error('Could not create temp dir for temp workspace');
 
   await createFiles(structure, [root]);