diff --git a/qtcompat_p.h b/qtcompat_p.h
index 12024b2249..05f173dc99 100644
--- a/qtcompat_p.h
+++ b/qtcompat_p.h
@@ -1,64 +1,64 @@
 /*
     Copyright (c) 2017 Kevin Funk <kfunk@.kde.org
 
     This library is free software; you can redistribute it and/or modify it
     under the terms of the GNU Library General Public License as published by
     the Free Software Foundation; either version 2 of the License, or (at your
     option) any later version.
 
     This library is distributed in the hope that it will be useful, but WITHOUT
     ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
     FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Library General Public
     License for more details.
 
     You should have received a copy of the GNU Library General Public License
     along with this library; see the file COPYING.LIB.  If not, write to the
     Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
     02110-1301, USA.
 */
 
 #ifndef KDEVELOP_QTCOMPAT_P_H
 #define KDEVELOP_QTCOMPAT_P_H
 
 #include <qglobal.h>
 
+// COMPAT: qAsConst (from qglobal.h)
 #if QT_VERSION < QT_VERSION_CHECK(5,7,0)
 namespace QtPrivate
 {
 template <typename T> struct QAddConst {
     typedef const T Type;
 };
 }
 
 // this adds const to non-const objects (like std::as_const)
 template <typename T>
 Q_DECL_CONSTEXPR typename QtPrivate::QAddConst<T>::Type &qAsConst(T &t) Q_DECL_NOTHROW { return t; }
 // prevent rvalue arguments:
 template <typename T>
 void qAsConst(const T &&) Q_DECL_EQ_DELETE;
 #endif
 
 #endif
 
-// compat for Q_FALLTHROUGH
+// COMPAT: Q_FALLTHROUGH (from qcompilerdetection.h)
 #if QT_VERSION < QT_VERSION_CHECK(5,8,0)
 
-#if defined(__has_cpp_attribute)
-#    if __has_cpp_attribute(fallthrough)
-#        define Q_FALLTHROUGH() [[fallthrough]]
-#    elif __has_cpp_attribute(clang::fallthrough)
-#        define Q_FALLTHROUGH() [[clang::fallthrough]]
-#    elif __has_cpp_attribute(gnu::fallthrough)
-#        define Q_FALLTHROUGH() [[gnu::fallthrough]]
-#    endif
+#if defined(__cplusplus)
+#if QT_HAS_CPP_ATTRIBUTE(fallthrough)
+#  define Q_FALLTHROUGH() [[fallthrough]]
+#elif QT_HAS_CPP_ATTRIBUTE(clang::fallthrough)
+#    define Q_FALLTHROUGH() [[clang::fallthrough]]
+#elif QT_HAS_CPP_ATTRIBUTE(gnu::fallthrough)
+#    define Q_FALLTHROUGH() [[gnu::fallthrough]]
+#endif
 #endif
-
 #ifndef Q_FALLTHROUGH
-#    if defined(__GNUC__) && !defined(__INTEL_COMPILER) && (((__GNUC__ * 100) + __GNUC_MINOR__) >= 700)
-#        define Q_FALLTHROUGH() __attribute__((fallthrough))
-#    else
-#        define Q_FALLTHROUGH() (void)0
-#    endif
+#  if (defined(Q_CC_GNU) && Q_CC_GNU >= 700) && !defined(Q_CC_INTEL)
+#    define Q_FALLTHROUGH() __attribute__((fallthrough))
+#  else
+#    define Q_FALLTHROUGH() (void)0
+#endif
 #endif
 
 #endif