diff --git a/library/x509_internal.h b/library/x509_internal.h
index 8a2d2ed007..78c529341a 100644
--- a/library/x509_internal.h
+++ b/library/x509_internal.h
@@ -12,6 +12,7 @@
 #include "mbedtls/private_access.h"
 
 #include "mbedtls/build_info.h"
+#include "common.h"
 
 #include "mbedtls/x509.h"
 #include "mbedtls/asn1.h"