diff --git a/modules/core/src/lib/layer-extension.ts b/modules/core/src/lib/layer-extension.ts
index 35b383fc879..fad438090dd 100644
--- a/modules/core/src/lib/layer-extension.ts
+++ b/modules/core/src/lib/layer-extension.ts
@@ -23,7 +23,7 @@ import type CompositeLayer from './composite-layer';
 import type {UpdateParameters} from './layer';
 import type {LayerContext} from './layer-manager';
 
-export default abstract class LayerExtension<OptionsT = undefined> {
+export default abstract class LayerExtension<OptionsT = unknown> {
   static defaultProps = {};
   opts!: OptionsT;