diff --git a/src/libs/utils/fileutils.cpp b/src/libs/utils/fileutils.cpp
index 2cc227c5729..22969d62a0b 100644
--- a/src/libs/utils/fileutils.cpp
+++ b/src/libs/utils/fileutils.cpp
@@ -44,7 +44,9 @@
 #endif
 
 #ifdef Q_OS_WIN
+#ifdef QTCREATOR_PCH_H
 #define CALLBACK WINAPI
+#endif
 #include <qt_windows.h>
 #include <shlobj.h>
 #endif
diff --git a/src/libs/utils/process_ctrlc_stub.cpp b/src/libs/utils/process_ctrlc_stub.cpp
index cf3dffaa4a9..1c37adec3c6 100644
--- a/src/libs/utils/process_ctrlc_stub.cpp
+++ b/src/libs/utils/process_ctrlc_stub.cpp
@@ -46,7 +46,7 @@
 #include <cstdlib>
 #include <cstdio>
 
-#ifndef CALLBACK
+#ifdef QTCREATOR_PCH_H
 #define CALLBACK WINAPI
 #endif
 
diff --git a/src/libs/utils/qtcprocess.cpp b/src/libs/utils/qtcprocess.cpp
index e1ce8682d0c..66e18e1760e 100644
--- a/src/libs/utils/qtcprocess.cpp
+++ b/src/libs/utils/qtcprocess.cpp
@@ -50,7 +50,9 @@
 #include <memory>
 
 #ifdef Q_OS_WIN
+#ifdef QTCREATOR_PCH_H
 #define CALLBACK WINAPI
+#endif
 #include <qt_windows.h>
 #else
 #include <errno.h>
diff --git a/src/plugins/debugger/registerpostmortemaction.cpp b/src/plugins/debugger/registerpostmortemaction.cpp
index ac9e8c53fbb..5a7e6312484 100644
--- a/src/plugins/debugger/registerpostmortemaction.cpp
+++ b/src/plugins/debugger/registerpostmortemaction.cpp
@@ -31,7 +31,9 @@
 #include <QDir>
 #include <QString>
 
+#ifdef QTCREATOR_PCH_H
 #define CALLBACK WINAPI
+#endif
 #include <windows.h>
 #include <objbase.h>
 #include <shellapi.h>
diff --git a/src/shared/qtcreator_gui_pch.h b/src/shared/qtcreator_gui_pch.h
index b25dbf67b70..af57b87ba73 100644
--- a/src/shared/qtcreator_gui_pch.h
+++ b/src/shared/qtcreator_gui_pch.h
@@ -27,6 +27,8 @@
  * This is a precompiled header file for use in Xcode / Mac GCC /
  * GCC >= 3.4 / VC to greatly speed the building of Qt Creator.
  */
+#ifndef QTCREATOR_GUI_PCH_H
+#define QTCREATOR_GUI_PCH_H
 
 #include "qtcreator_pch.h"
 
@@ -45,3 +47,5 @@
 #include <QWidget>
 
 #endif
+
+#endif // QTCREATOR_GUI_PCH_H
diff --git a/src/shared/qtcreator_pch.h b/src/shared/qtcreator_pch.h
index 4f93238efba..75e15967c51 100644
--- a/src/shared/qtcreator_pch.h
+++ b/src/shared/qtcreator_pch.h
@@ -26,8 +26,13 @@
 /*
  * This is a precompiled header file for use in Xcode / Mac GCC /
  * GCC >= 3.4 / VC to greatly speed the building of Qt Creator.
+ *
+ * The define below is checked in source code. Do not replace with #pragma once!
  */
 
+#ifndef QTCREATOR_PCH_H
+#define QTCREATOR_PCH_H
+
 #if defined __cplusplus
 #include <QtGlobal>
 
@@ -85,3 +90,5 @@ using Qt::noforcesign;
 
 #include <stdlib.h>
 #endif
+
+#endif // QTCREATOR_PCH_H