diff --git a/src/observableInterfaces.ts b/src/observableInterfaces.ts
index 527d7ea31..f8a5b45f0 100644
--- a/src/observableInterfaces.ts
+++ b/src/observableInterfaces.ts
@@ -529,5 +529,5 @@ export interface ComputedParams<T = any> {
 }
 
 export interface ComputedProxyParams<T = any> extends ComputedParams {
-    proxy: (fn: (key: string, params: ComputedParams<T>) => T) => void;
+    proxy: (fn: (key: string, params: ComputedParams<T>) => T | Promise<T>) => void;
 }