diff --git a/base/include/android-base/expected.h b/base/include/android-base/expected.h
index 08c9fb5..957a8a0 100644
--- a/base/include/android-base/expected.h
+++ b/base/include/android-base/expected.h
@@ -14,6 +14,8 @@
  * limitations under the License.
  */
 
+#pragma once
+
 #include <algorithm>
 #include <initializer_list>
 #include <type_traits>