diff --git a/lib/permissions/minimally-encoded-thread-permissions.js b/lib/permissions/minimally-encoded-thread-permissions.js
--- a/lib/permissions/minimally-encoded-thread-permissions.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.js
@@ -169,10 +169,21 @@
 ): $ReadOnlyArray<string> =>
   Object.keys(threadRolePermissionsBlob).map(rolePermissionToBitmaskHex);
 
+const decodeThreadRolePermissionsBitmaskArray = (
+  threadRolePermissionsBitmaskArray: $ReadOnlyArray<string>,
+): ThreadRolePermissionsBlob =>
+  Object.fromEntries(
+    threadRolePermissionsBitmaskArray.map(bitmask => [
+      decodeRolePermissionBitmask(bitmask),
+      true,
+    ]),
+  );
+
 export {
   permissionsToBitmaskHex,
   hasPermission,
   rolePermissionToBitmaskHex,
   decodeRolePermissionBitmask,
   threadRolePermissionsBlobToBitmaskArray,
+  decodeThreadRolePermissionsBitmaskArray,
 };
diff --git a/lib/permissions/minimally-encoded-thread-permissions.test.js b/lib/permissions/minimally-encoded-thread-permissions.test.js
--- a/lib/permissions/minimally-encoded-thread-permissions.test.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.test.js
@@ -2,6 +2,7 @@
 
 import {
   decodeRolePermissionBitmask,
+  decodeThreadRolePermissionsBitmaskArray,
   hasPermission,
   permissionsToBitmaskHex,
   rolePermissionToBitmaskHex,
@@ -128,82 +129,95 @@
   });
 });
 
-describe('threadRolePermissionsBlobToBitmaskArray', () => {
-  const permissions: ThreadRolePermissionsBlob = {
-    add_members: true,
-    child_open_join_thread: true,
-    create_sidebars: true,
-    create_subthreads: true,
-    descendant_open_know_of: true,
-    descendant_open_visible: true,
-    descendant_opentoplevel_join_thread: true,
-    edit_entries: true,
-    edit_message: true,
-    edit_permissions: true,
-    edit_thread: true,
-    edit_thread_avatar: true,
-    edit_thread_color: true,
-    edit_thread_description: true,
-    know_of: true,
-    leave_thread: true,
-    react_to_message: true,
-    remove_members: true,
-    visible: true,
-    voiced: true,
-    open_know_of: true,
-    open_visible: true,
-    opentoplevel_join_thread: true,
-    toplevel_know_of: true,
-    toplevel_visible: true,
-    opentoplevel_know_of: true,
-    opentoplevel_visible: true,
-    child_know_of: true,
-    child_visible: true,
-    child_opentoplevel_join_thread: true,
-    child_toplevel_know_of: true,
-    child_toplevel_visible: true,
-    child_opentoplevel_know_of: true,
-    child_opentoplevel_visible: true,
-  };
+const threadRolePermissionsBlob: ThreadRolePermissionsBlob = {
+  add_members: true,
+  child_open_join_thread: true,
+  create_sidebars: true,
+  create_subthreads: true,
+  descendant_open_know_of: true,
+  descendant_open_visible: true,
+  descendant_opentoplevel_join_thread: true,
+  edit_entries: true,
+  edit_message: true,
+  edit_permissions: true,
+  edit_thread: true,
+  edit_thread_avatar: true,
+  edit_thread_color: true,
+  edit_thread_description: true,
+  know_of: true,
+  leave_thread: true,
+  react_to_message: true,
+  remove_members: true,
+  visible: true,
+  voiced: true,
+  open_know_of: true,
+  open_visible: true,
+  opentoplevel_join_thread: true,
+  toplevel_know_of: true,
+  toplevel_visible: true,
+  opentoplevel_know_of: true,
+  opentoplevel_visible: true,
+  child_know_of: true,
+  child_visible: true,
+  child_opentoplevel_join_thread: true,
+  child_toplevel_know_of: true,
+  child_toplevel_visible: true,
+  child_opentoplevel_know_of: true,
+  child_opentoplevel_visible: true,
+};
+
+const threadRolePermissionsBitmaskArray = [
+  '0c0',
+  '0a9',
+  '090',
+  '080',
+  '005',
+  '015',
+  '0a7',
+  '030',
+  '110',
+  '0b0',
+  '040',
+  '120',
+  '060',
+  '050',
+  '000',
+  '0f0',
+  '100',
+  '0d0',
+  '010',
+  '020',
+  '001',
+  '011',
+  '0a3',
+  '002',
+  '012',
+  '003',
+  '013',
+  '008',
+  '018',
+  '0ab',
+  '00a',
+  '01a',
+  '00b',
+  '01b',
+];
 
+describe('threadRolePermissionsBlobToBitmaskArray', () => {
   it('should encode threadRolePermissionsBlob as bitmask array', () => {
-    const threadRolePermissionsBitmaskArray =
-      threadRolePermissionsBlobToBitmaskArray(permissions);
-    expect(threadRolePermissionsBitmaskArray).toEqual([
-      '0c0',
-      '0a9',
-      '090',
-      '080',
-      '005',
-      '015',
-      '0a7',
-      '030',
-      '110',
-      '0b0',
-      '040',
-      '120',
-      '060',
-      '050',
-      '000',
-      '0f0',
-      '100',
-      '0d0',
-      '010',
-      '020',
-      '001',
-      '011',
-      '0a3',
-      '002',
-      '012',
-      '003',
-      '013',
-      '008',
-      '018',
-      '0ab',
-      '00a',
-      '01a',
-      '00b',
-      '01b',
-    ]);
+    const arr = threadRolePermissionsBlobToBitmaskArray(
+      threadRolePermissionsBlob,
+    );
+    expect(arr).toEqual(threadRolePermissionsBitmaskArray);
+  });
+});
+
+describe('decodeThreadRolePermissionsBitmaskArray', () => {
+  it('should decode threadRolePermissionsBitmaskArray', () => {
+    expect(
+      decodeThreadRolePermissionsBitmaskArray(
+        threadRolePermissionsBitmaskArray,
+      ),
+    ).toEqual(threadRolePermissionsBlob);
   });
 });