diff --git a/src/blackmisc/blackmiscfreefunctions.cpp b/src/blackmisc/blackmiscfreefunctions.cpp
index e5d29e1d3..f4fa2d6b0 100644
--- a/src/blackmisc/blackmiscfreefunctions.cpp
+++ b/src/blackmisc/blackmiscfreefunctions.cpp
@@ -21,7 +21,7 @@
 #include "statusmessagelist.h"
 #include "pixmap.h"
 #include "iconlist.h"
-#include "identifier.h"
+#include "identifierlist.h"
 #include "eventallclasses.h"
 #include <QtNetwork/QHostInfo>
 #include <QProcessEnvironment>
@@ -33,6 +33,7 @@
  */
 void BlackMisc::Math::registerMetadata()
 {
+    // void
 }
 
 /*
@@ -107,6 +108,7 @@ void BlackMisc::registerMetadata()
     CLogCategoryList::registerMetadata();
     CPixmap::registerMetadata();
     CIdentifier::registerMetadata();
+    CIdentifierList::registerMetadata();
 
     // sub namespaces
     PhysicalQuantities::registerMetadata();
diff --git a/src/blackmisc/loghandler.cpp b/src/blackmisc/loghandler.cpp
index 0898f12dc..c6191ef15 100644
--- a/src/blackmisc/loghandler.cpp
+++ b/src/blackmisc/loghandler.cpp
@@ -29,8 +29,10 @@ namespace BlackMisc
         QMetaObject::invokeMethod(CLogHandler::instance(), "logLocalMessage", Q_ARG(BlackMisc::CStatusMessage, statusMessage));
     }
 
-    void CLogHandler::install()
+    void CLogHandler::install(bool skipIfAlreadyInstalled)
     {
+        if (skipIfAlreadyInstalled && m_oldHandler) { return; }
+        Q_ASSERT_X(!m_oldHandler, Q_FUNC_INFO, "Re-installing the log handler should be avoided");
         m_oldHandler = qInstallMessageHandler(messageHandler);
     }
 
@@ -107,6 +109,13 @@ namespace BlackMisc
         emit remoteMessageLogged(statusMessage);
     }
 
+    void BlackMisc::CLogHandler::enableConsoleOutput(bool enable)
+    {
+        Q_ASSERT_X(m_oldHandler, Q_FUNC_INFO, "Install the log handler before using it");
+        Q_ASSERT_X(thread() == QThread::currentThread(), Q_FUNC_INFO, "Wrong thread");
+        m_enableFallThrough = enable;
+    }
+
     void CLogHandler::logMessage(const CStatusMessage &statusMessage)
     {
         collectGarbage();
@@ -115,6 +124,7 @@ namespace BlackMisc
 
         if (isFallThroughEnabled(handlers))
         {
+            Q_ASSERT_X(m_oldHandler, Q_FUNC_INFO, "Handler must be installed");
             QtMsgType type;
             QString category;
             QString message;
diff --git a/src/blackmisc/loghandler.h b/src/blackmisc/loghandler.h
index 9787007eb..63eb7aef4 100644
--- a/src/blackmisc/loghandler.h
+++ b/src/blackmisc/loghandler.h
@@ -42,7 +42,7 @@ namespace BlackMisc
         static CLogHandler *instance();
 
         //! Tell the CLogHandler to install itself with qInstallMessageHandler.
-        void install();
+        void install(bool skipIfAlreadyInstalled = false);
 
         //! Return a pattern handler for subscribing to all messages which match the given pattern.
         //! \warning This must only be called from the main thread.
@@ -74,11 +74,7 @@ namespace BlackMisc
         void logRemoteMessage(const BlackMisc::CStatusMessage &message);
 
         //! Enable or disable the default Qt handler.
-        void enableConsoleOutput(bool enable)
-        {
-            Q_ASSERT(thread() == QThread::currentThread());
-            m_enableFallThrough = enable;
-        }
+        void enableConsoleOutput(bool enable);
 
     private:
         void logMessage(const BlackMisc::CStatusMessage &message);