diff --git a/include/mbedtls/x509_internal.h b/include/mbedtls/x509_internal.h
index c69c5421c..668d8fba0 100644
--- a/include/mbedtls/x509_internal.h
+++ b/include/mbedtls/x509_internal.h
@@ -25,6 +25,8 @@
 #ifndef MBEDTLS_X509_INTERNAL_H
 #define MBEDTLS_X509_INTERNAL_H
 
+#if defined(MBEDTLS_X509_USE_C)
+
 #include "x509.h"
 #include "threading.h"
 
@@ -118,4 +120,5 @@ static int mbedtls_x509_write_sig( unsigned char **p, unsigned char *start,
                     const char *oid, size_t oid_len,
                     unsigned char *sig, size_t size );
 #endif /* MBEDTLS_X509_CREATE_C */
+#endif /* MBEDTLS_X509_USE_C */
 #endif /* MBEDTLS_X509_INTERNAL_H */