diff --git a/ext/mysqlnd/mysqlnd_alloc.h b/ext/mysqlnd/mysqlnd_alloc.h
index bb1980cfcf0..deaef374896 100644
--- a/ext/mysqlnd/mysqlnd_alloc.h
+++ b/ext/mysqlnd/mysqlnd_alloc.h
@@ -83,4 +83,16 @@ static inline void mysqlnd_set_string(MYSQLND_STRING *buf, const char *string, s
 	}
 }
 
+static inline void mysqlnd_set_persistent_string(MYSQLND_STRING *buf, const char *string, size_t len, bool persistent) {
+	if (buf->s) {
+		mnd_pefree(buf->s, persistent);
+		buf->s = NULL;
+		buf->l = 0;
+	}
+	if (string) {
+		buf->s = mnd_pestrndup(string, len, persistent);
+		buf->l = len;
+	}
+}
+
 #endif /* MYSQLND_ALLOC_H */
diff --git a/ext/mysqlnd/mysqlnd_auth.c b/ext/mysqlnd/mysqlnd_auth.c
index 62d248c940e..421f4d082a3 100644
--- a/ext/mysqlnd/mysqlnd_auth.c
+++ b/ext/mysqlnd/mysqlnd_auth.c
@@ -99,10 +99,7 @@ mysqlnd_run_authentication(
 			switch_to_auth_protocol = NULL;
 			switch_to_auth_protocol_len = 0;
 
-			if (conn->authentication_plugin_data.s) {
-				mnd_pefree(conn->authentication_plugin_data.s, conn->persistent);
-				conn->authentication_plugin_data.s = NULL;
-			}
+			mysqlnd_set_persistent_string(&conn->authentication_plugin_data, NULL, 0, conn->persistent);
 			conn->authentication_plugin_data.l = plugin_data_len;
 			conn->authentication_plugin_data.s = mnd_pemalloc(conn->authentication_plugin_data.l, conn->persistent);
 			memcpy(conn->authentication_plugin_data.s, plugin_data, plugin_data_len);
@@ -490,24 +487,11 @@ mysqlnd_auth_change_user(MYSQLND_CONN_DATA * const conn,
 		}
 	}
 	if (ret == PASS) {
-		char * tmp = NULL;
-		/* if we get conn->username as parameter and then we first free it, then estrndup it, we will crash */
-		tmp = mnd_pestrndup(user, user_len, conn->persistent);
-		if (conn->username.s) {
-			mnd_pefree(conn->username.s, conn->persistent);
-		}
-		conn->username.s = tmp;
+		ZEND_ASSERT(conn->username.s != user && conn->password.s != passwd);
+		mysqlnd_set_persistent_string(&conn->username, user, user_len, conn->persistent);
+		mysqlnd_set_persistent_string(&conn->password, passwd, passwd_len, conn->persistent);
 
-		tmp = mnd_pestrdup(passwd, conn->persistent);
-		if (conn->password.s) {
-			mnd_pefree(conn->password.s, conn->persistent);
-		}
-		conn->password.s = tmp;
-
-		if (conn->last_message.s) {
-			mnd_efree(conn->last_message.s);
-			conn->last_message.s = NULL;
-		}
+		mysqlnd_set_string(&conn->last_message, NULL, 0);
 		UPSERT_STATUS_RESET(conn->upsert_status);
 		/* set charset for old servers */
 		if (conn->m->get_server_version(conn) < 50123) {
diff --git a/ext/mysqlnd/mysqlnd_commands.c b/ext/mysqlnd/mysqlnd_commands.c
index 5a7c8048257..40821bb1efe 100644
--- a/ext/mysqlnd/mysqlnd_commands.c
+++ b/ext/mysqlnd/mysqlnd_commands.c
@@ -107,11 +107,7 @@ MYSQLND_METHOD(mysqlnd_command, init_db)(MYSQLND_CONN_DATA * const conn, const M
 	*/
 	UPSERT_STATUS_SET_AFFECTED_ROWS_TO_ERROR(conn->upsert_status);
 	if (ret == PASS) {
-		if (conn->connect_or_select_db.s) {
-			mnd_pefree(conn->connect_or_select_db.s, conn->persistent);
-		}
-		conn->connect_or_select_db.s = mnd_pestrndup(db.s, db.l, conn->persistent);
-		conn->connect_or_select_db.l = db.l;
+		mysqlnd_set_persistent_string(&conn->connect_or_select_db, db.s, db.l, conn->persistent);
 	}
 
 	DBG_RETURN(ret);
diff --git a/ext/mysqlnd/mysqlnd_connection.c b/ext/mysqlnd/mysqlnd_connection.c
index 171daea883a..ce68e1f7048 100644
--- a/ext/mysqlnd/mysqlnd_connection.c
+++ b/ext/mysqlnd/mysqlnd_connection.c
@@ -282,31 +282,14 @@ MYSQLND_METHOD(mysqlnd_conn_data, free_contents)(MYSQLND_CONN_DATA * conn)
 
 	DBG_INF("Freeing memory of members");
 
-	if (conn->hostname.s) {
-		mnd_pefree(conn->hostname.s, pers);
-		conn->hostname.s = NULL;
-	}
-	if (conn->username.s) {
-		mnd_pefree(conn->username.s, pers);
-		conn->username.s = NULL;
-	}
-	if (conn->password.s) {
-		mnd_pefree(conn->password.s, pers);
-		conn->password.s = NULL;
-	}
-	if (conn->connect_or_select_db.s) {
-		mnd_pefree(conn->connect_or_select_db.s, pers);
-		conn->connect_or_select_db.s = NULL;
-	}
-	if (conn->unix_socket.s) {
-		mnd_pefree(conn->unix_socket.s, pers);
-		conn->unix_socket.s = NULL;
-	}
+	mysqlnd_set_persistent_string(&conn->hostname, NULL, 0, pers);
+	mysqlnd_set_persistent_string(&conn->username, NULL, 0, pers);
+	mysqlnd_set_persistent_string(&conn->password, NULL, 0, pers);
+	mysqlnd_set_persistent_string(&conn->connect_or_select_db, NULL, 0, pers);
+	mysqlnd_set_persistent_string(&conn->unix_socket, NULL, 0, pers);
 	DBG_INF_FMT("scheme=%s", conn->scheme.s);
-	if (conn->scheme.s) {
-		mnd_pefree(conn->scheme.s, pers);
-		conn->scheme.s = NULL;
-	}
+	mysqlnd_set_persistent_string(&conn->scheme, NULL, 0, pers);
+	
 	if (conn->server_version) {
 		mnd_pefree(conn->server_version, pers);
 		conn->server_version = NULL;
@@ -315,14 +298,8 @@ MYSQLND_METHOD(mysqlnd_conn_data, free_contents)(MYSQLND_CONN_DATA * conn)
 		mnd_pefree(conn->host_info, pers);
 		conn->host_info = NULL;
 	}
-	if (conn->authentication_plugin_data.s) {
-		mnd_pefree(conn->authentication_plugin_data.s, pers);
-		conn->authentication_plugin_data.s = NULL;
-	}
-	if (conn->last_message.s) {
-		mnd_efree(conn->last_message.s);
-		conn->last_message.s = NULL;
-	}
+	mysqlnd_set_persistent_string(&conn->authentication_plugin_data, NULL, 0, pers);
+	mysqlnd_set_string(&conn->last_message, NULL, 0);
 
 	conn->charset = NULL;
 	conn->greet_charset = NULL;
@@ -406,10 +383,7 @@ MYSQLND_METHOD(mysqlnd_conn_data, end_psession)(MYSQLND_CONN_DATA * conn)
 		conn->current_result->m.free_result(conn->current_result, TRUE);
 		conn->current_result = NULL;
 	}
-	if (conn->last_message.s) {
-		mnd_efree(conn->last_message.s);
-		conn->last_message.s = NULL;
-	}
+	mysqlnd_set_string(&conn->last_message, NULL, 0);
 	conn->error_info = &conn->error_info_impl;
 	DBG_RETURN(PASS);
 }
@@ -681,8 +655,7 @@ MYSQLND_METHOD(mysqlnd_conn_data, connect)(MYSQLND_CONN_DATA * conn,
 		pfc->data->compressed = mysql_flags & CLIENT_COMPRESS? TRUE:FALSE;
 
 
-		conn->scheme.s = mnd_pestrndup(transport.s, transport.l, conn->persistent);
-		conn->scheme.l = transport.l;
+		mysqlnd_set_persistent_string(&conn->scheme, transport.s, transport.l, conn->persistent);
 		if (transport.s) {
 			mnd_sprintf_free(transport.s);
 			transport.s = NULL;
@@ -692,17 +665,13 @@ MYSQLND_METHOD(mysqlnd_conn_data, connect)(MYSQLND_CONN_DATA * conn,
 			goto err; /* OOM */
 		}
 
-		conn->username.l		= username.l;
-		conn->username.s		= mnd_pestrndup(username.s, conn->username.l, conn->persistent);
-		conn->password.l		= password.l;
-		conn->password.s		= mnd_pestrndup(password.s, conn->password.l, conn->persistent);
+		mysqlnd_set_persistent_string(&conn->username, username.s, username.l, conn->persistent);
+		mysqlnd_set_persistent_string(&conn->password, username.s, password.l, conn->persistent);
 		conn->port				= port;
-		conn->connect_or_select_db.l = database.l;
-		conn->connect_or_select_db.s = mnd_pestrndup(database.s, conn->connect_or_select_db.l, conn->persistent);
+		mysqlnd_set_persistent_string(&conn->connect_or_select_db, database.s, database.l, conn->persistent);
 
 		if (!unix_socket && !named_pipe) {
-			conn->hostname.s = mnd_pestrndup(hostname.s, hostname.l, conn->persistent);
-			conn->hostname.l = hostname.l;
+			mysqlnd_set_persistent_string(&conn->hostname, hostname.s, hostname.l, conn->persistent);
 			{
 				char *p;
 				mnd_sprintf(&p, 0, "%s via TCP/IP", conn->hostname.s);
diff --git a/ext/mysqlnd/mysqlnd_wireprotocol.c b/ext/mysqlnd/mysqlnd_wireprotocol.c
index 445df72d902..77d0c31aa6d 100644
--- a/ext/mysqlnd/mysqlnd_wireprotocol.c
+++ b/ext/mysqlnd/mysqlnd_wireprotocol.c
@@ -1127,10 +1127,7 @@ void php_mysqlnd_rset_header_free_mem(void * _packet)
 {
 	MYSQLND_PACKET_RSET_HEADER *p= (MYSQLND_PACKET_RSET_HEADER *) _packet;
 	DBG_ENTER("php_mysqlnd_rset_header_free_mem");
-	if (p->info_or_local_file.s) {
-		mnd_efree(p->info_or_local_file.s);
-		p->info_or_local_file.s = NULL;
-	}
+	mysqlnd_set_string(&p->info_or_local_file, NULL, 0);
 	DBG_VOID_RETURN;
 }
 /* }}} */
@@ -1764,10 +1761,7 @@ static
 void php_mysqlnd_stats_free_mem(void * _packet)
 {
 	MYSQLND_PACKET_STATS *p= (MYSQLND_PACKET_STATS *) _packet;
-	if (p->message.s) {
-		mnd_efree(p->message.s);
-		p->message.s = NULL;
-	}
+	mysqlnd_set_string(&p->message, NULL, 0);
 }
 /* }}} */