diff --git a/keyserver/src/endpoints.js b/keyserver/src/endpoints.js
--- a/keyserver/src/endpoints.js
+++ b/keyserver/src/endpoints.js
@@ -15,16 +15,14 @@
   setThreadUnreadStatusValidator,
   updateActivityResponderInputValidator,
 } from 'lib/types/validators/activity-validators.js';
+import { deviceTokenUpdateRequestInputValidator } from 'lib/types/validators/device-validators.js';
 import { updateUserAvatarRequestValidator } from 'lib/utils/avatar-utils.js';
 
 import {
   updateActivityResponder,
   threadSetUnreadStatusResponder,
 } from './responders/activity-responders.js';
-import {
-  deviceTokenUpdateResponder,
-  deviceTokenUpdateRequestInputValidator,
-} from './responders/device-responders.js';
+import { deviceTokenUpdateResponder } from './responders/device-responders.js';
 import {
   entryFetchResponder,
   entryRevisionFetchResponder,
diff --git a/keyserver/src/responders/device-responders.js b/keyserver/src/responders/device-responders.js
--- a/keyserver/src/responders/device-responders.js
+++ b/keyserver/src/responders/device-responders.js
@@ -1,21 +1,10 @@
 // @flow
 
-import t from 'tcomb';
-import type { TInterface } from 'tcomb';
-
 import type { DeviceTokenUpdateRequest } from 'lib/types/device-types.js';
-import { tShape, tPlatformDetails } from 'lib/utils/validation-utils.js';
 
 import type { Viewer } from '../session/viewer.js';
 import { deviceTokenUpdater } from '../updaters/device-token-updaters.js';
 
-const deviceTokenUpdateRequestInputValidator: TInterface<DeviceTokenUpdateRequest> =
-  tShape<DeviceTokenUpdateRequest>({
-    deviceToken: t.maybe(t.String),
-    deviceType: t.maybe(t.enums.of(['ios', 'android'])),
-    platformDetails: t.maybe(tPlatformDetails),
-  });
-
 async function deviceTokenUpdateResponder(
   viewer: Viewer,
   request: DeviceTokenUpdateRequest,
@@ -23,4 +12,4 @@
   await deviceTokenUpdater(viewer, request);
 }
 
-export { deviceTokenUpdateRequestInputValidator, deviceTokenUpdateResponder };
+export { deviceTokenUpdateResponder };
diff --git a/lib/types/validators/device-validators.js b/lib/types/validators/device-validators.js
new file mode 100644
--- /dev/null
+++ b/lib/types/validators/device-validators.js
@@ -0,0 +1,13 @@
+// @flow
+import t from 'tcomb';
+import type { TInterface } from 'tcomb';
+
+import { tShape, tPlatformDetails } from '../../utils/validation-utils.js';
+import type { DeviceTokenUpdateRequest } from '../device-types.js';
+
+export const deviceTokenUpdateRequestInputValidator: TInterface<DeviceTokenUpdateRequest> =
+  tShape<DeviceTokenUpdateRequest>({
+    deviceToken: t.maybe(t.String),
+    deviceType: t.maybe(t.enums.of(['ios', 'android'])),
+    platformDetails: t.maybe(tPlatformDetails),
+  });