diff --git a/index.d.ts b/index.d.ts
index 3810013..0900b62 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -35,7 +35,7 @@ type ZCLEnum8Status = 'SUCCESS' | 'FAILURE' | 'NOT_AUTHORIZED' | 'RESERVED_FIELD
 
 export interface ZCLNodeCluster extends EventEmitter {
   /** Dynamic command handler methods (e.g. `onZoneStatusChangeNotification`). */
-  [key: string]: unknown;
+  [key: `on${string}`]: unknown;
 
   discoverCommandsGenerated(params?: {
     startValue?: number;
diff --git a/scripts/generate-types.js b/scripts/generate-types.js
index 4c71042..1f5097f 100644
--- a/scripts/generate-types.js
+++ b/scripts/generate-types.js
@@ -287,7 +287,7 @@ type ZCLEnum8Status = ${zclTypeToTS(ZCLDataTypes.enum8Status, false)};
   // Base ZCLNodeCluster interface
   lines.push(`export interface ZCLNodeCluster extends EventEmitter {
   /** Dynamic command handler methods (e.g. \`onZoneStatusChangeNotification\`). */
-  [key: string]: unknown;
+  [key: \`on\${string}\`]: unknown;
 
   discoverCommandsGenerated(params?: {
     startValue?: number;