diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 6167f56..617bdc7 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -395,10 +395,10 @@
     /*! The IV  for server->client records. */
     unsigned char server_write_iv[ MBEDTLS_MAX_IV_LENGTH ];
 
-    size_t keyLen; /*!< The length of client_write_key and
-                    *   server_write_key, in Bytes. */
-    size_t ivLen;  /*!< The length of client_write_iv and
-                    *   server_write_iv, in Bytes. */
+    size_t key_len; /*!< The length of client_write_key and
+                     *   server_write_key, in Bytes. */
+    size_t iv_len;  /*!< The length of client_write_iv and
+                     *   server_write_iv, in Bytes. */
 };
 typedef struct mbedtls_ssl_key_set mbedtls_ssl_key_set;
 #endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
diff --git a/library/ssl_tls13_keys.c b/library/ssl_tls13_keys.c
index 76c9398..c334dbc 100644
--- a/library/ssl_tls13_keys.c
+++ b/library/ssl_tls13_keys.c
@@ -185,7 +185,7 @@
                      mbedtls_md_type_t hash_alg,
                      const unsigned char *client_secret,
                      const unsigned char *server_secret,
-                     size_t slen, size_t keyLen, size_t ivLen,
+                     size_t slen, size_t key_len, size_t iv_len,
                      mbedtls_ssl_key_set *keys )
 {
     int ret = 0;
@@ -194,7 +194,7 @@
                     client_secret, slen,
                     MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
                     NULL, 0,
-                    keys->client_write_key, keyLen );
+                    keys->client_write_key, key_len );
     if( ret != 0 )
         return( ret );
 
@@ -202,7 +202,7 @@
                     server_secret, slen,
                     MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( key ),
                     NULL, 0,
-                    keys->server_write_key, keyLen );
+                    keys->server_write_key, key_len );
     if( ret != 0 )
         return( ret );
 
@@ -210,7 +210,7 @@
                     client_secret, slen,
                     MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
                     NULL, 0,
-                    keys->client_write_iv, ivLen );
+                    keys->client_write_iv, iv_len );
     if( ret != 0 )
         return( ret );
 
@@ -218,12 +218,12 @@
                     server_secret, slen,
                     MBEDTLS_SSL_TLS1_3_LBL_WITH_LEN( iv ),
                     NULL, 0,
-                    keys->server_write_iv, ivLen );
+                    keys->server_write_iv, iv_len );
     if( ret != 0 )
         return( ret );
 
-    keys->keyLen = keyLen;
-    keys->ivLen = ivLen;
+    keys->key_len = key_len;
+    keys->iv_len = iv_len;
 
     return( 0 );
 }
diff --git a/library/ssl_tls13_keys.h b/library/ssl_tls13_keys.h
index 9efeb04..62e94d3 100644
--- a/library/ssl_tls13_keys.h
+++ b/library/ssl_tls13_keys.h
@@ -129,8 +129,8 @@
  *                      This must be a readable buffer of size \p slen Bytes
  * \param slen          Length of the secrets \p client_secret and
  *                      \p server_secret in Bytes.
- * \param keyLen        The desired length of the key to be extracted in Bytes.
- * \param ivLen         The desired length of the IV to be extracted in Bytes.
+ * \param key_len       The desired length of the key to be extracted in Bytes.
+ * \param iv_len        The desired length of the IV to be extracted in Bytes.
  * \param keys          The address of the structure holding the generated
  *                      keys and IVs.
  *
@@ -142,7 +142,7 @@
                      mbedtls_md_type_t hash_alg,
                      const unsigned char *client_secret,
                      const unsigned char *server_secret,
-                     size_t slen, size_t keyLen, size_t ivLen,
+                     size_t slen, size_t key_len, size_t iv_len,
                      mbedtls_ssl_key_set *keys );
 
 /**
diff --git a/tests/suites/test_suite_ssl.function b/tests/suites/test_suite_ssl.function
index 6a2871f..58abef8 100644
--- a/tests/suites/test_suite_ssl.function
+++ b/tests/suites/test_suite_ssl.function
@@ -3726,19 +3726,19 @@
                      &keys ) == 0 );
 
     ASSERT_COMPARE( keys.client_write_key,
-                    keys.keyLen,
+                    keys.key_len,
                     expected_client_write_key->x,
                     (size_t) desired_key_len );
     ASSERT_COMPARE( keys.server_write_key,
-                    keys.keyLen,
+                    keys.key_len,
                     expected_server_write_key->x,
                     (size_t) desired_key_len );
     ASSERT_COMPARE( keys.client_write_iv,
-                    keys.ivLen,
+                    keys.iv_len,
                     expected_client_write_iv->x,
                     (size_t) desired_iv_len );
     ASSERT_COMPARE( keys.server_write_iv,
-                    keys.ivLen,
+                    keys.iv_len,
                     expected_server_write_iv->x,
                     (size_t) desired_iv_len );
 }