diff --git a/src/lib/base/String.h b/src/lib/base/String.h
index ab1b20089..567af1d25 100644
--- a/src/lib/base/String.h
+++ b/src/lib/base/String.h
@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include <cstdarg>
 #include <string>
 
 //! std::string utilities