diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index f552345f4..810873c51 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -987,7 +987,7 @@ void mbedtls_x509write_crt_init(mbedtls_x509write_cert *ctx);
  */
 void mbedtls_x509write_crt_set_version(mbedtls_x509write_cert *ctx, int version);
 
-#if defined(MBEDTLS_BIGNUM_C)
+#if defined(MBEDTLS_BIGNUM_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
 /**
  * \brief           Set the serial number for a Certificate.
  *
@@ -1005,8 +1005,9 @@ void mbedtls_x509write_crt_set_version(mbedtls_x509write_cert *ctx, int version)
  *
  * \return          0 if successful
  */
-int mbedtls_x509write_crt_set_serial(mbedtls_x509write_cert *ctx, const mbedtls_mpi *serial);
-#endif
+int MBEDTLS_DEPRECATED mbedtls_x509write_crt_set_serial(
+    mbedtls_x509write_cert *ctx, const mbedtls_mpi *serial);
+#endif // MBEDTLS_BIGNUM_C && !MBEDTLS_DEPRECATED_REMOVED
 
 /**
  * \brief           Set the serial number for a Certificate.
diff --git a/library/x509write_crt.c b/library/x509write_crt.c
index 53c2ac4ec..718b6f074 100644
--- a/library/x509write_crt.c
+++ b/library/x509write_crt.c
@@ -100,7 +100,7 @@ int mbedtls_x509write_crt_set_issuer_name(mbedtls_x509write_cert *ctx,
     return mbedtls_x509_string_to_names(&ctx->issuer, issuer_name);
 }
 
-#if defined(MBEDTLS_BIGNUM_C)
+#if defined(MBEDTLS_BIGNUM_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
 int mbedtls_x509write_crt_set_serial(mbedtls_x509write_cert *ctx,
                                      const mbedtls_mpi *serial)
 {
@@ -129,7 +129,7 @@ int mbedtls_x509write_crt_set_serial(mbedtls_x509write_cert *ctx,
 
     return 0;
 }
-#endif
+#endif // MBEDTLS_BIGNUM_C && !MBEDTLS_DEPRECATED_REMOVED
 
 int mbedtls_x509write_crt_set_serial_new(mbedtls_x509write_cert *ctx,
                                          char *serial_buff, size_t serial_buff_len)
diff --git a/programs/x509/cert_write.c b/programs/x509/cert_write.c
index 363ed8d8d..ec4d32527 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -663,7 +663,7 @@ usage:
     mbedtls_x509write_crt_set_version(&crt, opt.version);
     mbedtls_x509write_crt_set_md_alg(&crt, opt.md);
 
-#if defined(MBEDTLS_BIGNUM_C)
+#if defined(MBEDTLS_BIGNUM_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
     ret = mbedtls_x509write_crt_set_serial(&crt, &serial);
     if (ret != 0) {
         mbedtls_strerror(ret, buf, sizeof(buf));
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index 2bf8024ab..e09c4c5dc 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -384,15 +384,12 @@ void x509_crt_check(char *subject_key_file, char *subject_pwd,
         TEST_ASSERT(mbedtls_pk_get_type(&issuer_key) == MBEDTLS_PK_OPAQUE);
     }
 
-#if !defined(MBEDTLS_BIGNUM_C)
-    TEST_ASSERT(mbedtls_test_read_mpi(&serial, serial_str) == 0);
-#endif
-
     if (ver != -1) {
         mbedtls_x509write_crt_set_version(&crt, ver);
     }
 
-#if !defined(MBEDTLS_BIGNUM_C)
+#if defined(MBEDTLS_BIGNUM_C) && !defined(MBEDTLS_DEPRECATED_REMOVED)
+    TEST_ASSERT(mbedtls_test_read_mpi(&serial, serial_str) == 0);
     TEST_ASSERT(mbedtls_x509write_crt_set_serial(&crt, &serial) == 0);
 #else
     TEST_ASSERT(mbedtls_x509write_crt_set_serial_new(&crt, serial_str,