diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index c3b06110189..5370e258808 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -64,10 +64,6 @@
 #  define Q_DECL_IMPORT __declspec(dllimport)
 #  define QT_MAKE_UNCHECKED_ARRAY_ITERATOR(x) stdext::make_unchecked_array_iterator(x) // Since _MSC_VER >= 1800
 #  define QT_MAKE_CHECKED_ARRAY_ITERATOR(x, N) stdext::make_checked_array_iterator(x, size_t(N)) // Since _MSC_VER >= 1500
-#    undef Q_CC_MSVC_ONLY
-#    ifdef Q_CC_CLANG_ONLY
-#      undef Q_CC_CLANG_ONLY
-#    endif
 
 #elif defined(__BORLANDC__) || defined(__TURBOC__)
 #  define Q_CC_BOR