diff --git a/services/web/.storybook/preview.tsx b/services/web/.storybook/preview.tsx
index ef20079e18..e3d6d73f4a 100644
--- a/services/web/.storybook/preview.tsx
+++ b/services/web/.storybook/preview.tsx
@@ -74,6 +74,9 @@ function resetMeta() {
       'gv',
       'mf',
       'lhs',
+      'lean',
+      'lean4',
+      'hs',
       'mk',
       'xmpdata',
       'cfg',
diff --git a/services/web/config/settings.defaults.js b/services/web/config/settings.defaults.js
index 14be7ca372..eee3905ca2 100644
--- a/services/web/config/settings.defaults.js
+++ b/services/web/config/settings.defaults.js
@@ -60,6 +60,9 @@ const defaultTextExtensions = [
   'yml',
   'yaml',
   'lhs',
+  'lean',
+  'lean4',
+  'hs',
   'mk',
   'xmpdata',
   'cfg',
diff --git a/services/web/test/frontend/helpers/reset-meta.ts b/services/web/test/frontend/helpers/reset-meta.ts
index fdd2a86049..5c1f2ecaf1 100644
--- a/services/web/test/frontend/helpers/reset-meta.ts
+++ b/services/web/test/frontend/helpers/reset-meta.ts
@@ -44,6 +44,9 @@ export function resetMeta() {
       'gv',
       'mf',
       'lhs',
+      'lean',
+      'lean4',
+      'hs',
       'mk',
       'xmpdata',
       'cfg',
diff --git a/services/web/test/unit/src/History/RestoreManager.test.mjs b/services/web/test/unit/src/History/RestoreManager.test.mjs
index d2cf5a3245..03058842e2 100644
--- a/services/web/test/unit/src/History/RestoreManager.test.mjs
+++ b/services/web/test/unit/src/History/RestoreManager.test.mjs
@@ -129,6 +129,9 @@ describe('RestoreManager', function () {
           'yml',
           'yaml',
           'lhs',
+          'lean',
+          'lean4',
+          'hs',
           'mk',
           'xmpdata',
           'cfg',
diff --git a/services/web/test/unit/src/Uploads/FileTypeManager.test.mjs b/services/web/test/unit/src/Uploads/FileTypeManager.test.mjs
index 3564a58812..0ed8fea6b3 100644
--- a/services/web/test/unit/src/Uploads/FileTypeManager.test.mjs
+++ b/services/web/test/unit/src/Uploads/FileTypeManager.test.mjs
@@ -138,6 +138,9 @@ describe('FileTypeManager', function () {
         '/something/file.m',
         '/file.TEX',
         '/file.lhs',
+        '/file.lean',
+        '/file.lean4',
+        '/file.hs',
         '/file.xmpdata',
         '/file.cfg',
         '/file.Rnw',