diff --git a/packages/core/js-client/src/compilerSupport/callFunction.ts b/packages/core/js-client/src/compilerSupport/callFunction.ts
index 2d4970f8..cc927e81 100644
--- a/packages/core/js-client/src/compilerSupport/callFunction.ts
+++ b/packages/core/js-client/src/compilerSupport/callFunction.ts
@@ -50,7 +50,7 @@ export type CallAquaFunctionArgs = {
   config: CallAquaFunctionConfig | undefined;
   peer: FluencePeer;
   args: { [key: string]: JSONValue | ArgCallbackFunction };
-  fireAndForget: boolean | undefined;
+  fireAndForget?: boolean | undefined;
 };
 
 export type CallAquaFunctionConfig = {