diff --git a/library/ssl_client.c b/library/ssl_client.c
index 6d988a8..8892acf 100644
--- a/library/ssl_client.c
+++ b/library/ssl_client.c
@@ -765,11 +765,6 @@
           MBEDTLS_SSL_SESSION_TICKETS &&
           MBEDTLS_HAVE_TIME */
 
-    if (ssl->conf->f_rng == NULL) {
-        MBEDTLS_SSL_DEBUG_MSG(1, ("no RNG provided"));
-        return MBEDTLS_ERR_SSL_NO_RNG;
-    }
-
     /* Bet on the highest configured version if we are not in a TLS 1.2
      * renegotiation or session resumption.
      */
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index b09db1e..aa967d8 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -1361,6 +1361,11 @@
     }
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
 
+    if (ssl->conf->f_rng == NULL) {
+        MBEDTLS_SSL_DEBUG_MSG(1, ("no RNG provided"));
+        return MBEDTLS_ERR_SSL_NO_RNG;
+    }
+
     /* Space for further checks */
 
     return 0;
diff --git a/library/ssl_tls12_server.c b/library/ssl_tls12_server.c
index 5bee188..b49a8ae 100644
--- a/library/ssl_tls12_server.c
+++ b/library/ssl_tls12_server.c
@@ -2178,11 +2178,6 @@
     }
 #endif /* MBEDTLS_SSL_DTLS_HELLO_VERIFY */
 
-    if (ssl->conf->f_rng == NULL) {
-        MBEDTLS_SSL_DEBUG_MSG(1, ("no RNG provided"));
-        return MBEDTLS_ERR_SSL_NO_RNG;
-    }
-
     /*
      *     0  .   0   handshake type
      *     1  .   3   handshake length
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 3a968aa..5c24657 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -1973,10 +1973,6 @@
     int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     unsigned char *server_randbytes =
         ssl->handshake->randbytes + MBEDTLS_CLIENT_HELLO_RANDOM_LEN;
-    if (ssl->conf->f_rng == NULL) {
-        MBEDTLS_SSL_DEBUG_MSG(1, ("no RNG provided"));
-        return MBEDTLS_ERR_SSL_NO_RNG;
-    }
 
     if ((ret = ssl->conf->f_rng(ssl->conf->p_rng, server_randbytes,
                                 MBEDTLS_SERVER_HELLO_RANDOM_LEN)) != 0) {
diff --git a/tests/include/test/ssl_helpers.h b/tests/include/test/ssl_helpers.h
index 5b071f7..110e2ed 100644
--- a/tests/include/test/ssl_helpers.h
+++ b/tests/include/test/ssl_helpers.h
@@ -196,6 +196,13 @@
 #endif /* MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED */
 
 /*
+ * Random number generator aimed for TLS unitary tests. Its main purpose is to
+ * simplify the set-up of a random number generator for TLS
+ * unitary tests: no need to set up a good entropy source for example.
+ */
+int mbedtls_test_random(void *p_rng, unsigned char *output, size_t output_len);
+
+/*
  * This function can be passed to mbedtls to receive output logs from it. In
  * this case, it will count the instances of a mbedtls_test_ssl_log_pattern
  * in the received logged messages.
diff --git a/tests/src/test_helpers/ssl_helpers.c b/tests/src/test_helpers/ssl_helpers.c
index 5d4cb1c..045ed39 100644
--- a/tests/src/test_helpers/ssl_helpers.c
+++ b/tests/src/test_helpers/ssl_helpers.c
@@ -12,9 +12,7 @@
 #include "mbedtls/psa_util.h"
 
 #if defined(MBEDTLS_SSL_TLS_C)
-#if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
-static int rng_seed = 0xBEEF;
-static int rng_get(void *p_rng, unsigned char *output, size_t output_len)
+int mbedtls_test_random(void *p_rng, unsigned char *output, size_t output_len)
 {
     (void) p_rng;
     for (size_t i = 0; i < output_len; i++) {
@@ -23,7 +21,6 @@
 
     return 0;
 }
-#endif
 
 void mbedtls_test_ssl_log_analyzer(void *ctx, int level,
                                    const char *file, int line,
@@ -46,6 +43,8 @@
     mbedtls_test_handshake_test_options *opts)
 {
 #if defined(MBEDTLS_SSL_HANDSHAKE_WITH_CERT_ENABLED)
+    static int rng_seed = 0xBEEF;
+
     srand(rng_seed);
     rng_seed += 0xD0;
 #endif
@@ -755,7 +754,7 @@
 
     mbedtls_ssl_init(&(ep->ssl));
     mbedtls_ssl_config_init(&(ep->conf));
-    mbedtls_ssl_conf_rng(&(ep->conf), rng_get, NULL);
+    mbedtls_ssl_conf_rng(&(ep->conf), mbedtls_test_random, NULL);
 
     TEST_ASSERT(mbedtls_ssl_conf_get_user_data_p(&ep->conf) == NULL);
     TEST_EQUAL(mbedtls_ssl_conf_get_user_data_n(&ep->conf), 0);
diff --git a/tests/suites/test_suite_debug.function b/tests/suites/test_suite_debug.function
index eeefc95..70e7bad 100644
--- a/tests/suites/test_suite_debug.function
+++ b/tests/suites/test_suite_debug.function
@@ -2,6 +2,7 @@
 #include "debug_internal.h"
 #include "string.h"
 #include "mbedtls/pk.h"
+#include <test/ssl_helpers.h>
 
 struct buffer_data {
     char buf[2000];
@@ -65,11 +66,12 @@
     memset(buffer.buf, 0, 2000);
     buffer.ptr = buffer.buf;
 
-    mbedtls_ssl_config_defaults(&conf,
-                                MBEDTLS_SSL_IS_CLIENT,
-                                MBEDTLS_SSL_TRANSPORT_STREAM,
-                                MBEDTLS_SSL_PRESET_DEFAULT);
-
+    TEST_EQUAL(mbedtls_ssl_config_defaults(&conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT),
+               0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_dbg(&conf, string_debug, &buffer);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
@@ -103,11 +105,12 @@
     memset(buffer.buf, 0, 2000);
     buffer.ptr = buffer.buf;
 
-    mbedtls_ssl_config_defaults(&conf,
-                                MBEDTLS_SSL_IS_CLIENT,
-                                MBEDTLS_SSL_TRANSPORT_STREAM,
-                                MBEDTLS_SSL_PRESET_DEFAULT);
-
+    TEST_EQUAL(mbedtls_ssl_config_defaults(&conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT),
+               0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_dbg(&conf, string_debug, &buffer);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
@@ -138,11 +141,12 @@
     memset(buffer.buf, 0, 2000);
     buffer.ptr = buffer.buf;
 
-    mbedtls_ssl_config_defaults(&conf,
-                                MBEDTLS_SSL_IS_CLIENT,
-                                MBEDTLS_SSL_TRANSPORT_STREAM,
-                                MBEDTLS_SSL_PRESET_DEFAULT);
-
+    TEST_EQUAL(mbedtls_ssl_config_defaults(&conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT),
+               0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_dbg(&conf, string_debug, &buffer);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
@@ -175,11 +179,12 @@
     memset(buffer.buf, 0, 2000);
     buffer.ptr = buffer.buf;
 
-    mbedtls_ssl_config_defaults(&conf,
-                                MBEDTLS_SSL_IS_CLIENT,
-                                MBEDTLS_SSL_TRANSPORT_STREAM,
-                                MBEDTLS_SSL_PRESET_DEFAULT);
-
+    TEST_EQUAL(mbedtls_ssl_config_defaults(&conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT),
+               0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_dbg(&conf, string_debug, &buffer);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
@@ -214,11 +219,12 @@
     memset(buffer.buf, 0, 2000);
     buffer.ptr = buffer.buf;
 
-    mbedtls_ssl_config_defaults(&conf,
-                                MBEDTLS_SSL_IS_CLIENT,
-                                MBEDTLS_SSL_TRANSPORT_STREAM,
-                                MBEDTLS_SSL_PRESET_DEFAULT);
-
+    TEST_EQUAL(mbedtls_ssl_config_defaults(&conf,
+                                           MBEDTLS_SSL_IS_CLIENT,
+                                           MBEDTLS_SSL_TRANSPORT_STREAM,
+                                           MBEDTLS_SSL_PRESET_DEFAULT),
+               0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_dbg(&conf, string_debug, &buffer);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index d327828..2d124c5 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -1131,6 +1131,8 @@
                                             MBEDTLS_SSL_IS_CLIENT,
                                             MBEDTLS_SSL_TRANSPORT_DATAGRAM,
                                             MBEDTLS_SSL_PRESET_DEFAULT) == 0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
+
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
 
     /* Read previous record numbers */
@@ -2879,6 +2881,7 @@
     mbedtls_ssl_conf_transport(&conf, transport);
     mbedtls_ssl_conf_min_tls_version(&conf, min_tls_version);
     mbedtls_ssl_conf_max_tls_version(&conf, max_tls_version);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == expected_ssl_setup_result);
     TEST_EQUAL(mbedtls_ssl_conf_get_endpoint(
@@ -2920,6 +2923,8 @@
     mbedtls_ssl_init(&ssl);
     MD_OR_USE_PSA_INIT();
 
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
+
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
 
     TEST_ASSERT(ssl.handshake != NULL && ssl.handshake->group_list != NULL);
@@ -2951,6 +2956,7 @@
     mbedtls_ssl_config conf;
     mbedtls_ssl_config_init(&conf);
 
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
     mbedtls_ssl_conf_max_tls_version(&conf, MBEDTLS_SSL_VERSION_TLS1_2);
     mbedtls_ssl_conf_min_tls_version(&conf, MBEDTLS_SSL_VERSION_TLS1_2);
 
@@ -3059,6 +3065,7 @@
                                            MBEDTLS_SSL_TRANSPORT_DATAGRAM,
                                            MBEDTLS_SSL_PRESET_DEFAULT),
                0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
 
     TEST_EQUAL(mbedtls_ssl_setup(&ssl, &conf), 0);
     TEST_EQUAL(mbedtls_ssl_check_dtls_clihlo_cookie(&ssl, ssl.cli_id,
@@ -3113,6 +3120,7 @@
                                             MBEDTLS_SSL_TRANSPORT_STREAM,
                                             MBEDTLS_SSL_PRESET_DEFAULT)
                 == 0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
 
     TEST_ASSERT(mbedtls_ssl_setup(&ssl, &conf) == 0);
 
@@ -3371,6 +3379,7 @@
                                            MBEDTLS_SSL_IS_CLIENT,
                                            MBEDTLS_SSL_TRANSPORT_STREAM,
                                            MBEDTLS_SSL_PRESET_DEFAULT), 0);
+    mbedtls_ssl_conf_rng(&conf, mbedtls_test_random, NULL);
 
     TEST_EQUAL(mbedtls_ssl_setup(&ssl, &conf), 0);