diff --git a/include/proxysql_glovars.hpp b/include/proxysql_glovars.hpp
index 097708c0b..6b8b299f4 100644
--- a/include/proxysql_glovars.hpp
+++ b/include/proxysql_glovars.hpp
@@ -92,6 +92,7 @@ class ProxySQL_GlobalVariables {
 #ifdef PROXYSQLCLICKHOUSE
 		bool clickhouse_server;
 #endif /* PROXYSQLCLICKHOUSE */
+		pthread_mutex_t ext_glomth_mutex;
 	} global;
 	struct mysql {
 		char *server_version;
diff --git a/lib/MySQL_Thread.cpp b/lib/MySQL_Thread.cpp
index db10dd809..9db1fba7e 100644
--- a/lib/MySQL_Thread.cpp
+++ b/lib/MySQL_Thread.cpp
@@ -4731,6 +4731,7 @@ void MySQL_Thread::process_all_sessions() {
 }
 
 void MySQL_Thread::refresh_variables() {
+	pthread_mutex_lock(&GloVars.global.ext_glomth_mutex);
 	if (GloMTH==NULL) {
 		return;
 	}
@@ -4910,6 +4911,7 @@ void MySQL_Thread::refresh_variables() {
 	mysql_thread___session_debug=(bool)GloMTH->get_variable_int((char *)"session_debug");
 #endif /* DEBUG */
 	GloMTH->wrunlock();
+	pthread_mutex_unlock(&GloVars.global.ext_glomth_mutex);
 }
 
 MySQL_Thread::MySQL_Thread() {
diff --git a/lib/ProxySQL_GloVars.cpp b/lib/ProxySQL_GloVars.cpp
index 44570d7ad..323e7949b 100644
--- a/lib/ProxySQL_GloVars.cpp
+++ b/lib/ProxySQL_GloVars.cpp
@@ -100,6 +100,7 @@ ProxySQL_GlobalVariables::ProxySQL_GlobalVariables() :
 //	global.use_proxysql_mem=false;
 	pthread_mutex_init(&global.start_mutex,NULL);
 	pthread_mutex_init(&checksum_mutex,NULL);
+	pthread_mutex_init(&global.ext_glomth_mutex,NULL);
 	epoch_version = 0;
 	checksums_values.updates_cnt = 0;
 	checksums_values.dumped_at = 0;
diff --git a/src/main.cpp b/src/main.cpp
index 3cf2057b8..59c139831 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1173,8 +1173,10 @@ void ProxySQL_Main_shutdown_all_modules() {
 	}
 	if (GloMTH) {
 		cpu_timer t;
+		pthread_mutex_lock(&GloVars.global.ext_glomth_mutex);
 		delete GloMTH;
 		GloMTH=NULL;
+		pthread_mutex_unlock(&GloVars.global.ext_glomth_mutex);
 #ifdef DEBUG
 		std::cerr << "GloMTH shutdown in ";
 #endif