diff --git a/bids-validator/src/deps/path.ts b/bids-validator/src/deps/path.ts
index 244fb7b25..0c24472c3 100644
--- a/bids-validator/src/deps/path.ts
+++ b/bids-validator/src/deps/path.ts
@@ -5,6 +5,7 @@ export {
   basename,
   dirname,
   extname,
+  posix,
   fromFileUrl,
   parse,
   SEPARATOR_PATTERN,
diff --git a/bids-validator/src/files/browser.ts b/bids-validator/src/files/browser.ts
index 44ebb6eb9..190a0cb8a 100644
--- a/bids-validator/src/files/browser.ts
+++ b/bids-validator/src/files/browser.ts
@@ -1,7 +1,7 @@
 import { BIDSFile } from '../types/file.ts'
 import { FileTree } from '../types/filetree.ts'
 import { FileIgnoreRules } from './ignore.ts'
-import { parse, join, SEPARATOR_PATTERN } from '../deps/path.ts'
+import { parse, posix, SEPARATOR_PATTERN } from '../deps/path.ts'
 
 /**
  * Browser implement of BIDSFile wrapping native File/FileList types
@@ -68,7 +68,7 @@ export function fileListToTree(files: File[]): Promise<FileTree> {
         } else {
           // Otherwise make a new level and continue if needed
           const newTree = new FileTree(
-            join(currentLevelTree.path, level),
+            posix.join(currentLevelTree.path, level),
             level,
             currentLevelTree,
           )
diff --git a/bids-validator/src/files/deno.ts b/bids-validator/src/files/deno.ts
index ca15c4358..852e173a6 100644
--- a/bids-validator/src/files/deno.ts
+++ b/bids-validator/src/files/deno.ts
@@ -1,7 +1,7 @@
 /**
  * Deno specific implementation for reading files
  */
-import { join, basename } from '../deps/path.ts'
+import { posix, join, basename } from '../deps/path.ts'
 import { BIDSFile } from '../types/file.ts'
 import { FileTree } from '../types/filetree.ts'
 import { requestReadPermission } from '../setup/requestPermissions.ts'
@@ -122,7 +122,7 @@ export async function _readFileTree(
     if (dirEntry.isFile || dirEntry.isSymlink) {
       const file = new BIDSFileDeno(
         rootPath,
-        join(relativePath, dirEntry.name),
+        posix.join(relativePath, dirEntry.name),
         ignore,
       )
       // For .bidsignore, read in immediately and add the rules
@@ -134,7 +134,7 @@ export async function _readFileTree(
     if (dirEntry.isDirectory) {
       const dirTree = await _readFileTree(
         rootPath,
-        join(relativePath, dirEntry.name),
+        posix.join(relativePath, dirEntry.name),
         ignore,
         tree,
       )