diff --git a/library/x509_crt.c b/library/x509_crt.c
index 9d498ea..a1ecaa2 100644
--- a/library/x509_crt.c
+++ b/library/x509_crt.c
@@ -1413,6 +1413,7 @@
 }
 #endif /* MBEDTLS_FS_IO */
 
+#if defined(MBEDTLS_X509_INFO)
 static int x509_info_subject_alt_name( char **buf, size_t *size,
                                        const mbedtls_x509_sequence *subject_alt_name )
 {
@@ -1735,6 +1736,7 @@
 
     return( (int) ( size - n ) );
 }
+#endif /* MBEDTLS_X509_INFO */
 
 #if defined(MBEDTLS_X509_CHECK_KEY_USAGE)
 int mbedtls_x509_crt_check_key_usage( const mbedtls_x509_crt *crt,