diff --git a/tests/unit/s2n_server_cert_request_test.c b/tests/unit/s2n_server_cert_request_test.c
index 828eddfceb5..fbdd6392c92 100644
--- a/tests/unit/s2n_server_cert_request_test.c
+++ b/tests/unit/s2n_server_cert_request_test.c
@@ -60,7 +60,7 @@ int main(int argc, char **argv)
         EXPECT_NOT_NULL(server_conn = s2n_connection_new(S2N_SERVER));
         EXPECT_SUCCESS(s2n_connection_set_config(server_conn, server_config));
 
-        s2n_cert_req_send(server_conn);
+        EXPECT_SUCCESS(s2n_cert_req_send(server_conn));
         struct s2n_stuffer *in = &server_conn->handshake.io;
         uint8_t cert_types_len = 0;
 
@@ -88,7 +88,7 @@ int main(int argc, char **argv)
         EXPECT_SUCCESS(s2n_connection_set_config(server_conn, server_config));
         EXPECT_SUCCESS(s2n_config_enable_cert_req_dss_legacy_compat(server_config));
 
-        s2n_cert_req_send(server_conn);
+        EXPECT_SUCCESS(s2n_cert_req_send(server_conn));
         struct s2n_stuffer *in = &server_conn->handshake.io;
         uint8_t cert_types_len = 0;
 
@@ -105,6 +105,78 @@ int main(int argc, char **argv)
         EXPECT_SUCCESS(s2n_connection_free(server_conn));
     };
 
+    /* Test: certificate_authorities supported */
+    {
+        /* Test: no cert_authorities sent by default */
+        {
+            DEFER_CLEANUP(struct s2n_connection *conn = s2n_connection_new(S2N_SERVER),
+                    s2n_connection_ptr_free);
+            EXPECT_NOT_NULL(conn);
+            conn->actual_protocol_version = S2N_TLS12;
+
+            DEFER_CLEANUP(struct s2n_config *config = s2n_config_new(),
+                    s2n_config_ptr_free);
+            EXPECT_NOT_NULL(config);
+            EXPECT_SUCCESS(s2n_connection_set_config(conn, config));
+
+            EXPECT_SUCCESS(s2n_cert_req_send(conn));
+            struct s2n_stuffer *output = &conn->handshake.io;
+
+            uint8_t cert_types_len = 0;
+            EXPECT_SUCCESS(s2n_stuffer_read_uint8(output, &cert_types_len));
+            EXPECT_TRUE(cert_types_len > 0);
+            EXPECT_SUCCESS(s2n_stuffer_skip_read(output, cert_types_len));
+
+            uint16_t sig_algs_len = 0;
+            EXPECT_SUCCESS(s2n_stuffer_read_uint16(output, &sig_algs_len));
+            EXPECT_TRUE(sig_algs_len > 0);
+            EXPECT_SUCCESS(s2n_stuffer_skip_read(output, sig_algs_len));
+
+            uint16_t cert_authorities_len = 0;
+            EXPECT_SUCCESS(s2n_stuffer_read_uint16(output, &cert_authorities_len));
+            EXPECT_EQUAL(cert_authorities_len, 0);
+
+            EXPECT_EQUAL(s2n_stuffer_data_available(output), 0);
+        };
+
+        /* Test: cert_authorities sent if configured */
+        {
+            DEFER_CLEANUP(struct s2n_connection *conn = s2n_connection_new(S2N_SERVER),
+                    s2n_connection_ptr_free);
+            EXPECT_NOT_NULL(conn);
+
+            DEFER_CLEANUP(struct s2n_config *config = s2n_config_new(),
+                    s2n_config_ptr_free);
+            EXPECT_NOT_NULL(config);
+            EXPECT_SUCCESS(s2n_connection_set_config(conn, config));
+
+            /* If we use TLS1.1 instead of TLS1.2, we don't need to worry about
+             * skipping the signature algorithms.
+             */
+            conn->actual_protocol_version = S2N_TLS11;
+
+            const uint8_t ca_data[] = "these are my CAs";
+            EXPECT_SUCCESS(s2n_alloc(&config->cert_authorities, sizeof(ca_data)));
+            EXPECT_MEMCPY_SUCCESS(config->cert_authorities.data, ca_data, sizeof(ca_data));
+
+            EXPECT_SUCCESS(s2n_cert_req_send(conn));
+            struct s2n_stuffer *output = &conn->handshake.io;
+
+            uint8_t cert_types_len = 0;
+            EXPECT_SUCCESS(s2n_stuffer_read_uint8(output, &cert_types_len));
+            EXPECT_SUCCESS(s2n_stuffer_skip_read(output, cert_types_len));
+
+            uint16_t cert_authorities_len = 0;
+            EXPECT_SUCCESS(s2n_stuffer_read_uint16(output, &cert_authorities_len));
+            EXPECT_EQUAL(cert_authorities_len, sizeof(ca_data));
+
+            uint8_t *cert_authorities_data = s2n_stuffer_raw_read(output, cert_authorities_len);
+            EXPECT_NOT_NULL(cert_authorities_data);
+            EXPECT_BYTEARRAY_EQUAL(cert_authorities_data, ca_data, sizeof(ca_data));
+
+            EXPECT_EQUAL(s2n_stuffer_data_available(output), 0);
+        };
+    };
+
     END_TEST();
-    return 0;
 }
diff --git a/tls/extensions/s2n_cert_authorities.c b/tls/extensions/s2n_cert_authorities.c
index 8dd8415d7da..92dfe625201 100644
--- a/tls/extensions/s2n_cert_authorities.c
+++ b/tls/extensions/s2n_cert_authorities.c
@@ -83,7 +83,7 @@ int s2n_config_set_cert_authorities_from_trust_store(struct s2n_config *config,
     return S2N_SUCCESS;
 }
 
-static int s2n_cert_authorities_send(struct s2n_connection *conn, struct s2n_stuffer *out)
+int s2n_cert_authorities_send(struct s2n_connection *conn, struct s2n_stuffer *out)
 {
     POSIX_ENSURE_REF(conn);
     POSIX_ENSURE_REF(conn->config);
diff --git a/tls/s2n_server_cert_request.c b/tls/s2n_server_cert_request.c
index 79929a32cda..d2173960c20 100644
--- a/tls/s2n_server_cert_request.c
+++ b/tls/s2n_server_cert_request.c
@@ -17,6 +17,7 @@
 #include "crypto/s2n_certificate.h"
 #include "error/s2n_errno.h"
 #include "extensions/s2n_extension_list.h"
+#include "extensions/s2n_cert_authorities.h"
 #include "stuffer/s2n_stuffer.h"
 #include "tls/s2n_cipher_suites.h"
 #include "tls/s2n_config.h"
@@ -174,10 +175,8 @@ int s2n_cert_req_send(struct s2n_connection *conn)
         POSIX_GUARD_RESULT(s2n_signature_algorithms_supported_list_send(conn, out));
     }
 
-    /* RFC 5246 7.4.4 - If the certificate_authorities list is empty, then the
-     * client MAY send any certificate of the appropriate ClientCertificateType */
-    uint16_t acceptable_cert_authorities_len = 0;
-    POSIX_GUARD(s2n_stuffer_write_uint16(out, acceptable_cert_authorities_len));
+    /* In TLS1.2, certificate_authorities is part of the message instead of an extension */
+    POSIX_GUARD(s2n_cert_authorities_send(conn, out));
 
-    return 0;
+    return S2N_SUCCESS;
 }