diff --git a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
index b05f67e530c9..44c9b052bea0 100644
--- a/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
+++ b/llvm/utils/gn/secondary/libcxx/include/BUILD.gn
@@ -268,6 +268,7 @@ if (current_toolchain == default_toolchain) {
       "__format/concepts.h",
       "__format/enable_insertable.h",
       "__format/format_arg.h",
+      "__format/format_arg_store.h",
       "__format/format_args.h",
       "__format/format_context.h",
       "__format/format_error.h",