diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index c565b60..6898bd4 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -46,6 +46,8 @@
 #include "hash_info.h"
 #endif /* MBEDTLS_USE_PSA_CRYPTO */
 
+#include "legacy_or_psa.h"
+
 void mbedtls_x509write_crt_init( mbedtls_x509write_cert *ctx )
 {
     memset( ctx, 0, sizeof( mbedtls_x509write_cert ) );
@@ -172,7 +174,7 @@
                              is_ca, buf + sizeof(buf) - len, len ) );
 }
 
-#if defined(MBEDTLS_SHA1_C)
+#if defined(MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA)
 static int mbedtls_x509write_crt_set_key_identifier( mbedtls_x509write_cert *ctx,
                                               int is_ca,
                                               unsigned char tag )
@@ -254,7 +256,7 @@
                                                      1,
                                                      (MBEDTLS_ASN1_CONTEXT_SPECIFIC | 0) );
 }
-#endif /* MBEDTLS_SHA1_C */
+#endif /* MBEDTLS_HAS_ALG_SHA_1_VIA_MD_OR_PSA */
 
 int mbedtls_x509write_crt_set_key_usage( mbedtls_x509write_cert *ctx,
                                          unsigned int key_usage )