diff --git a/base/string_piece.h b/base/string_piece.h
index 5b4bf40e..70c0480 100644
--- a/base/string_piece.h
+++ b/base/string_piece.h
@@ -17,6 +17,7 @@
 
 #ifndef BASE_STRING_PIECE_H_
 #define BASE_STRING_PIECE_H_
+#pragma once
 
 #include <algorithm>
 #include <iosfwd>