diff --git a/packages/react-ai-sdk/src/rsc/VercelRSCAdapter.tsx b/packages/react-ai-sdk/src/rsc/VercelRSCAdapter.tsx
index e2ad65358..4da56665d 100644
--- a/packages/react-ai-sdk/src/rsc/VercelRSCAdapter.tsx
+++ b/packages/react-ai-sdk/src/rsc/VercelRSCAdapter.tsx
@@ -7,7 +7,7 @@ type RSCMessageConverter<T> = {
 };
 
 type VercelRSCAdapterBase<T> = {
-  isRunning: boolean;
+  isRunning?: boolean | undefined;
   messages: T[];
 
   onNew?: (message: AppendMessage) => Promise<void>;
diff --git a/packages/react/src/runtimes/external-store/ExternalStoreAdapter.tsx b/packages/react/src/runtimes/external-store/ExternalStoreAdapter.tsx
index 52e4c0aca..aad9713fd 100644
--- a/packages/react/src/runtimes/external-store/ExternalStoreAdapter.tsx
+++ b/packages/react/src/runtimes/external-store/ExternalStoreAdapter.tsx
@@ -12,8 +12,8 @@ type ExternalStoreMessageConverterAdapter<T> = {
 };
 
 type ExternalStoreAdapterBase<T> = {
-  threadId?: string;
-  isRunning?: boolean;
+  threadId?: string | undefined;
+  isRunning?: boolean | undefined;
   messages: T[];
   setMessages?: ((messages: T[]) => void) | undefined;
   onNew: (message: AppendMessage) => Promise<void>;