diff --git a/README.md b/README.md
index 36647a90c..15c0ea607 100755
--- a/README.md
+++ b/README.md
@@ -182,6 +182,7 @@ The ports used by SRS:
 
 ## V4 changes
 
+* v4.0, 2021-05-06, RTC: Fix config bug for nack and twcc. 4.0.99
 * v4.0, 2021-05-04, Add video room demo. 4.0.98
 * v4.0, 2021-05-03, Add RTC stream merging demo by FFmpeg. 4.0.97
 * v4.0, 2021-05-02, Add one to one demo. 4.0.96
diff --git a/trunk/src/app/srs_app_config.cpp b/trunk/src/app/srs_app_config.cpp
index 8c575a01e..76bb71eb3 100644
--- a/trunk/src/app/srs_app_config.cpp
+++ b/trunk/src/app/srs_app_config.cpp
@@ -3939,7 +3939,8 @@ srs_error_t SrsConfig::check_normal_config()
             } else if (n == "rtc") {
                 for (int j = 0; j < (int)conf->directives.size(); j++) {
                     string m = conf->at(j)->name;
-                    if (m != "enabled" && m != "bframe" && m != "aac" && m != "stun_timeout" && m != "stun_strict_check"
+                    if (m != "enabled" && m != "nack" && m != "twcc" && m != "nack_no_copy"
+                        && m != "bframe" && m != "aac" && m != "stun_timeout" && m != "stun_strict_check"
                         && m != "dtls_role" && m != "dtls_version" && m != "drop_for_pt" && m != "rtc_to_rtmp"
                         && m != "pli_for_rtmp") {
                         return srs_error_new(ERROR_SYSTEM_CONFIG_INVALID, "illegal vhost.rtc.%s of %s", m.c_str(), vhost->arg0().c_str());
diff --git a/trunk/src/core/srs_core_version4.hpp b/trunk/src/core/srs_core_version4.hpp
index 30cccb4d5..3c6df669c 100644
--- a/trunk/src/core/srs_core_version4.hpp
+++ b/trunk/src/core/srs_core_version4.hpp
@@ -26,6 +26,6 @@
 
 #define VERSION_MAJOR       4
 #define VERSION_MINOR       0
-#define VERSION_REVISION    98
+#define VERSION_REVISION    99
 
 #endif