diff --git a/library/x509_internal.h b/library/x509_internal.h
index ec1ac50..36cbc65 100644
--- a/library/x509_internal.h
+++ b/library/x509_internal.h
@@ -11,6 +11,7 @@
 #define MBEDTLS_X509_INTERNAL_H
 
 #include "common.h"
+#include "mbedtls/build_info.h"
 #include "mbedtls/private_access.h"
 
 #include "mbedtls/x509.h"