diff --git a/library/x509write_csr.c b/library/x509write_csr.c
index e7f547f03b..0fac775106 100644
--- a/library/x509write_csr.c
+++ b/library/x509write_csr.c
@@ -142,7 +142,7 @@ static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
     unsigned char hash[MBEDTLS_MD_MAX_SIZE];
     size_t pub_len = 0, sig_and_oid_len = 0, sig_len;
     size_t len = 0;
-    mbedtls_pk_type_t pk_alg;
+    mbedtls_pk_sigalg_t pk_alg;
     size_t hash_len;
     psa_algorithm_t hash_alg = mbedtls_md_psa_alg_from_type(ctx->md_alg);
 
@@ -219,19 +219,19 @@ static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
     }
 
     if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_RSA)) {
-        pk_alg = MBEDTLS_PK_RSA;
+        pk_alg = MBEDTLS_PK_SIGALG_RSA_PKCS1V15;
     } else if (mbedtls_pk_can_do(ctx->key, MBEDTLS_PK_ECDSA)) {
-        pk_alg = MBEDTLS_PK_ECDSA;
+        pk_alg = MBEDTLS_PK_SIGALG_ECDSA;
     } else {
         return MBEDTLS_ERR_X509_INVALID_ALG;
     }
 
-    if ((ret = mbedtls_pk_sign_ext((mbedtls_pk_sigalg_t) pk_alg, ctx->key, ctx->md_alg, hash, 0,
+    if ((ret = mbedtls_pk_sign_ext(pk_alg, ctx->key, ctx->md_alg, hash, 0,
                                    sig, sig_size, &sig_len)) != 0) {
         return ret;
     }
 
-    if ((ret = mbedtls_x509_oid_get_oid_by_sig_alg((mbedtls_pk_sigalg_t) pk_alg, ctx->md_alg,
+    if ((ret = mbedtls_x509_oid_get_oid_by_sig_alg(pk_alg, ctx->md_alg,
                                                    &sig_oid, &sig_oid_len)) != 0) {
         return ret;
     }
@@ -250,7 +250,7 @@ static int x509write_csr_der_internal(mbedtls_x509write_csr *ctx,
     c2 = buf + size;
     MBEDTLS_ASN1_CHK_ADD(sig_and_oid_len,
                          mbedtls_x509_write_sig(&c2, buf + len, sig_oid, sig_oid_len,
-                                                sig, sig_len, (mbedtls_pk_sigalg_t) pk_alg));
+                                                sig, sig_len, pk_alg));
 
     /*
      * Compact the space between the CSR data and signature by moving the