diff --git a/src/corelib/global/qcompilerdetection.h b/src/corelib/global/qcompilerdetection.h
index 3a6f02db17f..db5f6f3bb1c 100644
--- a/src/corelib/global/qcompilerdetection.h
+++ b/src/corelib/global/qcompilerdetection.h
@@ -499,7 +499,7 @@
 //    at least since 13.1, but I can't test further back
 #     define Q_COMPILER_BINARY_LITERALS
 #  endif
-#  if __cplusplus >= 201103L
+#  if __cplusplus >= 201103L || defined(__INTEL_CXX11_MODE__)
 #    if __INTEL_COMPILER >= 1200
 #      define Q_COMPILER_AUTO_TYPE
 #      define Q_COMPILER_CLASS_ENUM
@@ -517,7 +517,9 @@
 #      define Q_COMPILER_AUTO_FUNCTION
 #      define Q_COMPILER_NULLPTR
 #      define Q_COMPILER_TEMPLATE_ALIAS
-#      define Q_COMPILER_UNICODE_STRINGS
+#      ifndef _CHAR16T      // MSVC headers
+#        define Q_COMPILER_UNICODE_STRINGS
+#      endif
 #      define Q_COMPILER_VARIADIC_TEMPLATES
 #    endif
 #    if __INTEL_COMPILER >= 1300
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 19e368defc4..e93bfbcc4a0 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -35,7 +35,11 @@
 #ifndef QGLOBAL_H
 #define QGLOBAL_H
 
-#include <stddef.h>
+#ifdef __cplusplus
+#  include <cstddef>
+#else
+#  include <stddef.h>
+#endif
 
 #define QT_VERSION_STR   "5.5.0"
 /*