diff --git a/x-pack/legacy/plugins/maps/common/constants.ts b/x-pack/legacy/plugins/maps/common/constants.ts
index e2c4a9e83f2b46..87d7f11b0875d8 100644
--- a/x-pack/legacy/plugins/maps/common/constants.ts
+++ b/x-pack/legacy/plugins/maps/common/constants.ts
@@ -4,7 +4,6 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 import { i18n } from '@kbn/i18n';
-import { EMSXYZSourceType } from './descriptor_types';
 export const EMS_CATALOGUE_PATH = 'ems/catalogue';
 
 export const EMS_FILES_CATALOGUE_PATH = 'ems/files';
@@ -54,7 +53,7 @@ export const EMS_FILE = 'EMS_FILE';
 export const ES_GEO_GRID = 'ES_GEO_GRID';
 export const ES_SEARCH = 'ES_SEARCH';
 export const ES_PEW_PEW = 'ES_PEW_PEW';
-export const EMS_XYZ: EMSXYZSourceType = 'EMS_XYZ';
+export const EMS_XYZ = 'EMS_XYZ'; // identifies a custom TMS source. Name is a little unfortunate.
 
 export const FIELD_ORIGIN = {
   SOURCE: 'source',
diff --git a/x-pack/legacy/plugins/maps/common/descriptor_types.d.ts b/x-pack/legacy/plugins/maps/common/descriptor_types.d.ts
index e3738454e7e473..c024721dfb870f 100644
--- a/x-pack/legacy/plugins/maps/common/descriptor_types.d.ts
+++ b/x-pack/legacy/plugins/maps/common/descriptor_types.d.ts
@@ -4,17 +4,13 @@
  * you may not use this file except in compliance with the Elastic License.
  */
 
-export type EMSXYZSourceType = 'EMS_XYZ';
-export type SourceType = EMSXYZSourceType | string;
-
 export interface ISourceDescriptor {
   id: string;
-  type: SourceType;
+  type: string;
 }
 
 export interface IXYZTMSSourceDescriptor extends ISourceDescriptor {
   urlTemplate: string;
-  type: EMSXYZSourceType;
 }
 
 export interface ILayerDescriptor {