diff --git a/src/components/layer.ts b/src/components/layer.ts
index 115b21d9..a1e53dd0 100644
--- a/src/components/layer.ts
+++ b/src/components/layer.ts
@@ -8,8 +8,9 @@ import type {MapInstance, AnyLayer, CustomLayerInterface} from '../types';
 // Omiting property from a union type, see
 // https://github.com/microsoft/TypeScript/issues/39556#issuecomment-656925230
 type OptionalId<T> = T extends {id: string} ? Omit<T, 'id'> & {id?: string} : T;
+type OptionalSource<T> = T extends {source: string} ? Omit<T, 'source'> & {source?: string} : T;
 
-export type LayerProps = OptionalId<AnyLayer | CustomLayerInterface> & {
+export type LayerProps = OptionalSource<OptionalId<AnyLayer | CustomLayerInterface>> & {
   /** If set, the layer will be inserted before the specified layer */
   beforeId?: string;
 };