diff --git a/include/mbedtls/x509_crt.h b/include/mbedtls/x509_crt.h
index 5a9da98bf1..25d4a7ba3c 100644
--- a/include/mbedtls/x509_crt.h
+++ b/include/mbedtls/x509_crt.h
@@ -996,7 +996,7 @@ 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.
  *
@@ -1014,8 +1014,9 @@ 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 618c51e18e..04226b8920 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 )
 {
@@ -126,7 +126,7 @@ 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 be3464e02d..f9d5102add 100644
--- a/programs/x509/cert_write.c
+++ b/programs/x509/cert_write.c
@@ -723,7 +723,7 @@ int main( int argc, char *argv[] )
     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 )
     {
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index c6ebc229e5..77115ca571 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -377,14 +377,11 @@ void x509_crt_check( char *subject_key_file, char *subject_pwd,
     if( pk_wrap == 2 )
         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,