diff --git a/maxscale-system-test/CMakeLists.txt b/maxscale-system-test/CMakeLists.txt
index 4bb197822..b1a571d15 100644
--- a/maxscale-system-test/CMakeLists.txt
+++ b/maxscale-system-test/CMakeLists.txt
@@ -973,6 +973,11 @@ add_test_executable(mxs1985_kill_hang.cpp mxs1985_kill_hang replication LABELS R
 # https://jira.mariadb.org/browse/MXS-2037
 add_test_executable(mxs2037_namedserver_wildcards.cpp mxs2037_namedserver_wildcards mxs2037_namedserver_wildcards LABELS namedserverfilter LIGHT REPL_BACKEND)
 
+# MXS-2043: Error "The MariaDB server is running with the --read-only option"
+#           for "select for update"
+# https://jira.mariadb.org/browse/MXS-2043
+add_test_executable(mxs2043_select_for_update.cpp mxs2043_select_for_update replication LABELS REPL_BACKEND)
+
 configure_file(templates.h.in templates.h @ONLY)
 
 include(CTest)
diff --git a/maxscale-system-test/mxs2043_select_for_update.cpp b/maxscale-system-test/mxs2043_select_for_update.cpp
new file mode 100644
index 000000000..952c91dc3
--- /dev/null
+++ b/maxscale-system-test/mxs2043_select_for_update.cpp
@@ -0,0 +1,172 @@
+/*
+ * Copyright (c) 2018 MariaDB Corporation Ab
+ *
+ * Use of this software is governed by the Business Source License included
+ * in the LICENSE.TXT file and at www.mariadb.com/bsl11.
+ *
+ * Change Date: 2022-01-01
+ *
+ * On the date above, in accordance with the Business Source License, use
+ * of this software will be governed by version 2 or later of the General
+ * Public License.
+ */
+
+#include "testconnections.h"
+
+//
+// This test makes all slaves read_only and then executes
+//
+//     SELECT ... FOR UPDATE
+//
+// first using the default system test user (that has super privileges)
+// and then using a custom user that only has SELECT and UPDATE grants.
+//
+// Before MXS-2043, a "SELECT ... FOR UPDATE" was classified as
+// QUERY_TYPE_READ, which caused the statement to be sent to a slave.
+//
+// With autocommit==1 and no transaction active there should be no problem
+// as FOR UPDATE should have no effect unless autocommit==0 or a transaction
+// is active (https://mariadb.com/kb/en/library/for-update/), but apparently
+// the server checks the read_only state first and rejects the query.
+//
+// After MXS-2043, a "SELECT ... FOR UPDATE" statement is classified as
+// QUERY_TYPE_WRITE, which unconditionally causes it to be sent to the master.
+//
+
+namespace
+{
+
+const char* ZUSER     = "mxs2043_user";
+const char* ZPASSWORD = "mxs2043_user";
+const char* ZTABLE    = "test.mxs2043";
+const char* ZCOLUMN   = "col";
+
+void drop_table(TestConnections& test, MYSQL* pMysql, bool silent = false)
+{
+    if (!silent)
+    {
+        test.tprintf("Dropping table.");
+    }
+
+    test.try_query(pMysql, "DROP TABLE IF EXISTS %s", ZTABLE);
+}
+
+bool create_table(TestConnections& test, MYSQL* pMysql)
+{
+    test.tprintf("Creating table.");
+
+    drop_table(test, pMysql, true);
+
+    test.try_query(pMysql, "CREATE TABLE %s (%s INT)", ZTABLE, ZCOLUMN);
+
+    return test.global_result == 0;
+}
+
+void drop_user(TestConnections& test, MYSQL* pMysql, bool silent = false)
+{
+    if (!silent)
+    {
+        test.tprintf("Dropping user.");
+    }
+
+    test.try_query(pMysql, "DROP USER IF EXISTS '%s'@'%%'", ZUSER);
+}
+
+bool create_user(TestConnections& test, MYSQL* pMysql)
+{
+    test.tprintf("Creating user.");
+
+    drop_user(test, pMysql, true);
+
+    test.try_query(pMysql, "CREATE USER '%s' IDENTIFIED by '%s'", ZUSER, ZPASSWORD);
+    test.try_query(pMysql, "GRANT SELECT, UPDATE ON %s TO '%s'@'%%'", ZTABLE, ZUSER);
+
+    return test.global_result == 0;
+}
+
+bool set_read_only_on_slaves(TestConnections& test, bool set)
+{
+    test.tprintf("%s read only on slaves.", set ? "Setting" : "Removing");
+
+    Mariadb_nodes& ms = *test.repl;
+
+    for (int i = 0; i < ms.N; ++i)
+    {
+        if (i != ms.master)
+        {
+            test.try_query(ms.nodes[i], "set global read_only=%d", set ? 1 : 0);
+        }
+    }
+
+    return test.global_result == 0;
+}
+
+void select_for_update(TestConnections& test, MYSQL* pMysql)
+{
+    test.try_query(pMysql, "SELECT %s FROM %s FOR UPDATE", ZCOLUMN, ZTABLE);
+}
+
+void run_test(TestConnections& test)
+{
+    // The default user has super privileges, so this should succeed
+    // whether or not MaxScale sends the query to the master or to
+    // some slave.
+
+    test.tprintf("Running test with default user.");
+    select_for_update(test, test.maxscales->conn_rwsplit[0]);
+
+    Maxscales& maxscales = *test.maxscales;
+
+    MYSQL* pMysql = open_conn(maxscales.rwsplit_port[0], maxscales.IP[0],
+                              ZUSER, ZPASSWORD);
+    test.expect(pMysql, "Could not open connections for %s.", ZUSER);
+
+    if (pMysql)
+    {
+        test.tprintf("Running test with created user.");
+
+        // The created user does not have super privileges, so this should
+        // fail unless MaxScale routes the query to the master.
+        select_for_update(test, pMysql);
+
+        mysql_close(pMysql);
+    }
+}
+
+}
+
+int main(int argc, char* argv[])
+{
+    TestConnections test(argc, argv);
+
+    Maxscales& maxscales = *test.maxscales;
+
+    maxscales.connect();
+
+    MYSQL* pMysql = maxscales.conn_rwsplit[0];
+
+    if (create_table(test, pMysql))
+    {
+        if (create_user(test, pMysql))
+        {
+            int rv = test.repl->connect();
+            test.expect(rv == 0, "Could not connect to MS.");
+
+            if (rv == 0)
+            {
+                if (set_read_only_on_slaves(test, true))
+                {
+                    run_test(test);
+                }
+
+                set_read_only_on_slaves(test, false);
+            }
+
+            drop_user(test, pMysql);
+        }
+
+        drop_table(test, pMysql);
+    }
+
+    return test.global_result;
+}