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
@@ -9,8 +9,13 @@
   ThreadPermissionsInfo,
   ThreadRolePermissionsBlob,
 } from '../types/thread-permission-types.js';
-import type { RoleInfo, ThreadCurrentUserInfo } from '../types/thread-types.js';
+import type {
+  MemberInfo,
+  RoleInfo,
+  ThreadCurrentUserInfo,
+} from '../types/thread-types.js';
 import {
+  memberInfoValidator,
   roleInfoValidator,
   threadCurrentUserInfoValidator,
 } from '../types/thread-types.js';
@@ -211,6 +216,17 @@
     permissions: tHexEncodedPermissionsBitmask,
   });
 
+export type MinimallyEncodedMemberInfo = {
+  ...MemberInfo,
+  +permissions: string,
+};
+
+const minimallyEncodedMemberInfoValidator: TInterface<MinimallyEncodedMemberInfo> =
+  tShape<MinimallyEncodedMemberInfo>({
+    ...memberInfoValidator.meta.props,
+    permissions: tHexEncodedPermissionsBitmask,
+  });
+
 export {
   permissionsToBitmaskHex,
   hasPermission,
@@ -220,4 +236,5 @@
   decodeThreadRolePermissionsBitmaskArray,
   minimallyEncodedRoleInfoValidator,
   minimallyEncodedThreadCurrentUserInfoValidator,
+  minimallyEncodedMemberInfoValidator,
 };
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
@@ -4,6 +4,7 @@
   decodeRolePermissionBitmask,
   decodeThreadRolePermissionsBitmaskArray,
   hasPermission,
+  minimallyEncodedMemberInfoValidator,
   minimallyEncodedRoleInfoValidator,
   minimallyEncodedThreadCurrentUserInfoValidator,
   permissionsToBitmaskHex,
@@ -323,3 +324,49 @@
     ).toBe(false);
   });
 });
+
+describe('minimallyEncodedMemberInfoValidator', () => {
+  it('should validate correctly formed MinimallyEncodedMemberInfo', () => {
+    expect(
+      minimallyEncodedMemberInfoValidator.is({
+        id: 'memberID',
+        permissions: 'ABCDEF',
+        isSender: true,
+      }),
+    ).toBe(true);
+
+    expect(
+      minimallyEncodedMemberInfoValidator.is({
+        id: 'memberID',
+        permissions: '01b',
+        isSender: false,
+      }),
+    ).toBe(true);
+  });
+
+  it('should NOT validate malformed MinimallyEncodedMemberInfo', () => {
+    expect(
+      minimallyEncodedMemberInfoValidator.is({
+        id: 'memberID',
+        permissions: 'INVALID',
+        isSender: false,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedMemberInfoValidator.is({
+        id: 'memberID',
+        permissions: 100,
+        isSender: false,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedMemberInfoValidator.is({
+        id: 'memberID',
+        permissions: 'ABCDEFABCDEFABCDE',
+        isSender: false,
+      }),
+    ).toBe(false);
+  });
+});
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -41,7 +41,7 @@
   +permissions: ThreadPermissionsInfo,
   +isSender: boolean,
 };
-const memberInfoValidator = tShape<MemberInfo>({
+export const memberInfoValidator: TInterface<MemberInfo> = tShape<MemberInfo>({
   id: t.String,
   role: t.maybe(tID),
   permissions: threadPermissionsInfoValidator,