diff --git a/Certificates.hpp b/Certificates.hpp
index c489559..c29ec3c 100644
--- a/Certificates.hpp
+++ b/Certificates.hpp
@@ -1,3 +1,4 @@
+#pragma once
 #include <cstdint>
 
 extern uint8_t attestCert[557];
diff --git a/U2F_Init_Response.hpp b/U2F_Init_Response.hpp
index 619d14e..bd940cf 100644
--- a/U2F_Init_Response.hpp
+++ b/U2F_Init_Response.hpp
@@ -1,3 +1,4 @@
+#pragma once
 #include <cstdint>
 #include "U2FMessage.hpp"
 #include "Field.hpp"