diff --git a/sandboxed_api/sandbox2/sandbox2.h b/sandboxed_api/sandbox2/sandbox2.h
index 8f6b319..5f55530 100644
--- a/sandboxed_api/sandbox2/sandbox2.h
+++ b/sandboxed_api/sandbox2/sandbox2.h
@@ -60,6 +60,7 @@ class Sandbox2 final {
   Sandbox2(const Sandbox2&) = delete;
   Sandbox2& operator=(const Sandbox2&) = delete;
 
+  // Runs the sandbox, blocking until there is a result.
   ABSL_MUST_USE_RESULT Result Run() {
     RunAsync();
     return AwaitResult();