diff --git a/tests/unit/s2n_alerts_protocol_test.c b/tests/unit/s2n_alerts_protocol_test.c
index d566448b092..441d566b52b 100644
--- a/tests/unit/s2n_alerts_protocol_test.c
+++ b/tests/unit/s2n_alerts_protocol_test.c
@@ -270,8 +270,8 @@ int main(int argc, char **argv)
                 case S2N_ERR_CERT_UNTRUSTED:
                     EXPECT_SUCCESS(s2n_connection_set_config(client, untrusted_config));
 
-                    EXPECT_FAILURE_WITH_ERRNO(s2n_negotiate_test_server_and_client(server, client),
-                            S2N_ERR_CERT_UNTRUSTED);
+                    EXPECT_FAILURE_WITH_ALERT(s2n_negotiate_test_server_and_client(server, client),
+                            S2N_ERR_CERT_UNTRUSTED, S2N_TLS_ALERT_CERTIFICATE_UNKNOWN);
 
                     failed_conn = client;
                     closed_conn = server;
diff --git a/tests/unit/s2n_mutual_auth_test.c b/tests/unit/s2n_mutual_auth_test.c
index c3d307cbd1e..520653ed029 100644
--- a/tests/unit/s2n_mutual_auth_test.c
+++ b/tests/unit/s2n_mutual_auth_test.c
@@ -369,8 +369,8 @@ int main(int argc, char **argv)
             EXPECT_SUCCESS(s2n_connection_set_io_pair(client_conn, &io_pair));
             EXPECT_SUCCESS(s2n_connection_set_io_pair(server_conn, &io_pair));
 
-            EXPECT_FAILURE_WITH_ERRNO(s2n_negotiate_test_server_and_client(server_conn, client_conn),
-                    S2N_ERR_CERT_UNTRUSTED);
+            EXPECT_FAILURE_WITH_ALERT(s2n_negotiate_test_server_and_client(server_conn, client_conn),
+                    S2N_ERR_CERT_UNTRUSTED, S2N_TLS_ALERT_CERTIFICATE_UNKNOWN);
 
             /* Ensure that a client certificate was received on the server, indicating that the
              * validation error occurred when processing the client's certificate, rather than the
diff --git a/tls/s2n_alerts.c b/tls/s2n_alerts.c
index 73c46c63da9..8766331b887 100644
--- a/tls/s2n_alerts.c
+++ b/tls/s2n_alerts.c
@@ -65,6 +65,52 @@ static S2N_RESULT s2n_translate_protocol_error_to_alert(int error_code, uint8_t
 
         S2N_ALERT_CASE(S2N_ERR_KTLS_KEYUPDATE, S2N_TLS_ALERT_UNEXPECTED_MESSAGE);
 
+        /* For errors involving certificates */
+
+        /* This error is used in several ways so make it a general certificate issue
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# certificate_unknown:  Some other (unspecified) issue arose in
+         *#    processing the certificate, rendering it unacceptable.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_UNTRUSTED, S2N_TLS_ALERT_CERTIFICATE_UNKNOWN);
+
+        /*
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# certificate_revoked:  A certificate was revoked by its signer.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_REVOKED, S2N_TLS_ALERT_CERTIFICATE_REVOKED);
+
+        /*
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# certificate_expired:  A certificate has expired or is not currently
+         *#    valid.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_NOT_YET_VALID, S2N_TLS_ALERT_CERTIFICATE_EXPIRED);
+        S2N_ALERT_CASE(S2N_ERR_CERT_EXPIRED, S2N_TLS_ALERT_CERTIFICATE_EXPIRED);
+
+        /*
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# unsupported_certificate:  A certificate was of an unsupported type.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_TYPE_UNSUPPORTED, S2N_TLS_ALERT_UNSUPPORTED_CERTIFICATE);
+
+        /*
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# access_denied:  A valid certificate or PSK was received, but when
+         *#    access control was applied, the sender decided not to proceed with
+         *#    negotiation.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_REJECTED, S2N_TLS_ALERT_ACCESS_DENIED);
+
+        /*
+         *= https://www.rfc-editor.org/rfc/rfc8446#section-6.2
+         *# bad_certificate:  A certificate was corrupt, contained signatures
+         *#    that did not verify correctly, etc.
+         */
+        S2N_ALERT_CASE(S2N_ERR_CERT_MAX_CHAIN_DEPTH_EXCEEDED, S2N_TLS_ALERT_BAD_CERTIFICATE);
+        S2N_ALERT_CASE(S2N_ERR_CERT_INVALID, S2N_TLS_ALERT_BAD_CERTIFICATE);
+        S2N_ALERT_CASE(S2N_ERR_DECODE_CERTIFICATE, S2N_TLS_ALERT_BAD_CERTIFICATE);
+
         /* TODO: Add mappings for other protocol errors.
          */
         S2N_NO_ALERT(S2N_ERR_ENCRYPT);
@@ -87,7 +133,6 @@ static S2N_RESULT s2n_translate_protocol_error_to_alert(int error_code, uint8_t
         S2N_NO_ALERT(S2N_ERR_HASH_WIPE_FAILED);
         S2N_NO_ALERT(S2N_ERR_HASH_NOT_READY);
         S2N_NO_ALERT(S2N_ERR_ALLOW_MD5_FOR_FIPS_FAILED);
-        S2N_NO_ALERT(S2N_ERR_DECODE_CERTIFICATE);
         S2N_NO_ALERT(S2N_ERR_DECODE_PRIVATE_KEY);
         S2N_NO_ALERT(S2N_ERR_INVALID_HELLO_RETRY);
         S2N_NO_ALERT(S2N_ERR_INVALID_SIGNATURE_ALGORITHM);
@@ -108,14 +153,6 @@ static S2N_RESULT s2n_translate_protocol_error_to_alert(int error_code, uint8_t
         S2N_NO_ALERT(S2N_ERR_SHUTDOWN_CLOSED);
         S2N_NO_ALERT(S2N_ERR_NON_EMPTY_RENEGOTIATION_INFO);
         S2N_NO_ALERT(S2N_ERR_RECORD_LIMIT);
-        S2N_NO_ALERT(S2N_ERR_CERT_UNTRUSTED);
-        S2N_NO_ALERT(S2N_ERR_CERT_REVOKED);
-        S2N_NO_ALERT(S2N_ERR_CERT_NOT_YET_VALID);
-        S2N_NO_ALERT(S2N_ERR_CERT_EXPIRED);
-        S2N_NO_ALERT(S2N_ERR_CERT_TYPE_UNSUPPORTED);
-        S2N_NO_ALERT(S2N_ERR_CERT_INVALID);
-        S2N_NO_ALERT(S2N_ERR_CERT_MAX_CHAIN_DEPTH_EXCEEDED);
-        S2N_NO_ALERT(S2N_ERR_CERT_REJECTED);
         S2N_NO_ALERT(S2N_ERR_CRL_LOOKUP_FAILED);
         S2N_NO_ALERT(S2N_ERR_CRL_SIGNATURE);
         S2N_NO_ALERT(S2N_ERR_CRL_ISSUER);