diff --git a/absl/synchronization/notification.h b/absl/synchronization/notification.h
index 82d111a..9a354ca 100644
--- a/absl/synchronization/notification.h
+++ b/absl/synchronization/notification.h
@@ -57,6 +57,7 @@
 #include "absl/time/time.h"
 
 namespace absl {
+ABSL_NAMESPACE_BEGIN
 
 // -----------------------------------------------------------------------------
 // Notification
@@ -73,7 +74,9 @@
   // Notification::HasBeenNotified()
   //
   // Returns the value of the notification's internal "notified" state.
-  bool HasBeenNotified() const;
+  bool HasBeenNotified() const {
+    return HasBeenNotifiedInternal(&this->notified_yet_);
+  }
 
   // Notification::WaitForNotification()
   //
@@ -105,10 +108,16 @@
   void Notify();
 
  private:
+  static inline bool HasBeenNotifiedInternal(
+      const std::atomic<bool>* notified_yet) {
+    return notified_yet->load(std::memory_order_acquire);
+  }
+
   mutable Mutex mutex_;
   std::atomic<bool> notified_yet_;  // written under mutex_
 };
 
+ABSL_NAMESPACE_END
 }  // namespace absl
 
 #endif  // ABSL_SYNCHRONIZATION_NOTIFICATION_H_