diff --git a/src/blackmisc/atomicfile.cpp b/src/blackmisc/atomicfile.cpp
index 05cf29d4c..41948010b 100644
--- a/src/blackmisc/atomicfile.cpp
+++ b/src/blackmisc/atomicfile.cpp
@@ -73,7 +73,7 @@ namespace BlackMisc
 
     QString CAtomicFile::randomSuffix()
     {
-        Q_CONSTEXPR auto max = 2176782335;
+        constexpr auto max = 2176782335;
         return QString::number(std::uniform_int_distribution<std::decay<decltype(max)>::type>(0, max)(Private::defaultRandomGenerator()), 36);
     }
 
diff --git a/src/blackmisc/range.h b/src/blackmisc/range.h
index 2e754d5f9..e505609ef 100644
--- a/src/blackmisc/range.h
+++ b/src/blackmisc/range.h
@@ -45,7 +45,7 @@ namespace BlackMisc
      */
     //! @{
     template <class T>
-    Q_CONSTEXPR typename std::add_const<T>::type &as_const(T &v) Q_DECL_NOEXCEPT { return v; }
+    constexpr typename std::add_const<T>::type &as_const(T &v) Q_DECL_NOEXCEPT { return v; }
     template <class T>
     void as_const(const T &&) = delete;
     //! @}
diff --git a/src/blackmisc/variantprivate.h b/src/blackmisc/variantprivate.h
index 718f59a67..c9c9a066d 100644
--- a/src/blackmisc/variantprivate.h
+++ b/src/blackmisc/variantprivate.h
@@ -232,7 +232,7 @@ namespace BlackMisc
         template <typename T, bool IsRegisteredMetaType /* = true */>
         struct MetaTypeHelperImpl
         {
-            static Q_DECL_CONSTEXPR int maybeGetMetaTypeId() { return qMetaTypeId<T>(); }
+            static constexpr int maybeGetMetaTypeId() { return qMetaTypeId<T>(); }
             static void maybeRegisterMetaType() { qRegisterMetaType<T>(); qDBusRegisterMetaType<T>(); registerMetaValueType<T>(); }
             static QVariant maybeToQVariant(const T &obj) { return QVariant::fromValue(obj); }
             static void maybeConvertFromQVariant(T &obj, const QVariant &var) { BlackMisc::setFromQVariant(&obj, var); }
@@ -241,7 +241,7 @@ namespace BlackMisc
         template <typename T>
         struct MetaTypeHelperImpl<T, /* IsRegisteredMetaType = */ false>
         {
-            static Q_DECL_CONSTEXPR int maybeGetMetaTypeId() { return QMetaType::UnknownType; }
+            static constexpr int maybeGetMetaTypeId() { return QMetaType::UnknownType; }
             static void maybeRegisterMetaType() {}
             static QVariant maybeToQVariant(const T &) { return {}; }
             static void maybeConvertFromQVariant(T &, const QVariant &) {}
diff --git a/src/plugins/simulator/fsx/simulatorfsx.cpp b/src/plugins/simulator/fsx/simulatorfsx.cpp
index 739242ac3..6ee2357e3 100644
--- a/src/plugins/simulator/fsx/simulatorfsx.cpp
+++ b/src/plugins/simulator/fsx/simulatorfsx.cpp
@@ -839,7 +839,7 @@ namespace BlackSimPlugin
             ISimulatorListener(info),
             m_timer(new QTimer(this))
         {
-            Q_CONSTEXPR int QueryInterval = 5 * 1000; // 5 seconds
+            constexpr int QueryInterval = 5 * 1000; // 5 seconds
             m_timer->setInterval(QueryInterval);
             this->m_timer->setObjectName(this->objectName().append(":m_timer"));
             connect(m_timer, &QTimer::timeout, this, &CSimulatorFsxListener::ps_checkConnection);