diff --git a/query_classifier/qc_sqlite/qc_sqlite.cc b/query_classifier/qc_sqlite/qc_sqlite.cc
index 661aac4ab..ff0a2d4ca 100644
--- a/query_classifier/qc_sqlite/qc_sqlite.cc
+++ b/query_classifier/qc_sqlite/qc_sqlite.cc
@@ -4413,14 +4413,12 @@ static int32_t qc_sqlite_process_init(void)
 
         this_unit.initialized = true;
 
-        if (qc_sqlite_thread_init() == 0)
+        if (this_unit.log_level != QC_LOG_NOTHING)
         {
-            if (this_unit.log_level != QC_LOG_NOTHING)
-            {
-                const char* message = NULL;
+            const char* message = NULL;
 
-                switch (this_unit.log_level)
-                {
+            switch (this_unit.log_level)
+            {
                 case QC_LOG_NON_PARSED:
                     message = "Statements that cannot be parsed completely are logged.";
                     break;
@@ -4435,16 +4433,9 @@ static int32_t qc_sqlite_process_init(void)
 
                 default:
                     ss_dassert(!true);
-                }
-
-                MXS_NOTICE("%s", message);
             }
-        }
-        else
-        {
-            this_unit.initialized = false;
 
-            sqlite3_shutdown();
+            MXS_NOTICE("%s", message);
         }
     }
     else
diff --git a/query_classifier/test/compare.cc b/query_classifier/test/compare.cc
index bb19165ca..47fe617c8 100644
--- a/query_classifier/test/compare.cc
+++ b/query_classifier/test/compare.cc
@@ -176,8 +176,9 @@ QUERY_CLASSIFIER* get_classifier(const char* zName, qc_sql_mode_t sql_mode, cons
 
     if (pClassifier)
     {
-        if ((pClassifier->qc_setup(sql_mode, zArgs) != QC_RESULT_OK) ||
-            ((pClassifier->qc_process_init() != QC_RESULT_OK)))
+        if (pClassifier->qc_setup(sql_mode, zArgs) != QC_RESULT_OK ||
+            pClassifier->qc_process_init() != QC_RESULT_OK ||
+            pClassifier->qc_thread_init() != QC_RESULT_OK)
         {
             cerr << "error: Could not setup or init classifier " << zName << "." << endl;
             qc_unload(pClassifier);
diff --git a/server/core/worker.cc b/server/core/worker.cc
index 93b443ab4..d01888a9d 100644
--- a/server/core/worker.cc
+++ b/server/core/worker.cc
@@ -857,11 +857,19 @@ void Worker::delete_zombies()
 
 void Worker::run()
 {
-    this_thread.current_worker_id = m_id;
-    poll_waitevents();
-    this_thread.current_worker_id = WORKER_ABSENT_ID;
+    if (modules_thread_init())
+    {
+        this_thread.current_worker_id = m_id;
+        poll_waitevents();
+        this_thread.current_worker_id = WORKER_ABSENT_ID;
 
-    MXS_NOTICE("Worker %d has shut down.", m_id);
+        MXS_NOTICE("Worker %d has shut down.", m_id);
+        modules_thread_finish();
+    }
+    else
+    {
+        MXS_ERROR("Could not perform thread initialization for all modules. Thread exits.");
+    }
 }
 
 bool Worker::start(size_t stack_size)
@@ -1069,18 +1077,8 @@ void Worker::handle_message(MessageQueue& queue, const MessageQueue::Message& ms
 //static
 void Worker::thread_main(void* pArg)
 {
-    if (modules_thread_init())
-    {
-        Worker* pWorker = static_cast<Worker*>(pArg);
-
-        pWorker->run();
-
-        modules_thread_finish();
-    }
-    else
-    {
-        MXS_ERROR("Could not perform thread initialization for all modules. Thread exits.");
-    }
+    Worker* pWorker = static_cast<Worker*>(pArg);
+    pWorker->run();
 }
 
 /**
diff --git a/server/modules/filter/dbfwfilter/dbfwfilter.cc b/server/modules/filter/dbfwfilter/dbfwfilter.cc
index 9db364770..637e7542b 100644
--- a/server/modules/filter/dbfwfilter/dbfwfilter.cc
+++ b/server/modules/filter/dbfwfilter/dbfwfilter.cc
@@ -92,6 +92,9 @@ int dbfw_yyparse(void*);
 #endif
 MXS_END_DECLS
 
+namespace
+{
+
 /** The rules and users for each thread */
 struct DbfwThread
 {
@@ -107,6 +110,8 @@ struct DbfwThread
 
 thread_local DbfwThread* this_thread = NULL;
 
+}
+
 bool parse_at_times(const char** tok, char** saveptr, Rule* ruledef);
 bool parse_limit_queries(Dbfw* instance, Rule* ruledef, const char* rule, char** saveptr);
 static void rule_free_all(Rule* rule);
@@ -450,6 +455,7 @@ bool dbfw_show_rules_json(const MODULECMD_ARG *argv, json_t** output)
 
 static int dbfw_thr_init()
 {
+    ss_dassert(this_thread == NULL);
     int rval = 0;
 
     if ((this_thread = new (std::nothrow) DbfwThread) == NULL)