diff --git a/include/wx/compiler.h b/include/wx/compiler.h
index 655c3be740..4d334d74d9 100644
--- a/include/wx/compiler.h
+++ b/include/wx/compiler.h
@@ -106,36 +106,8 @@
 #endif
 
 /*
-   This macro can be used to check that the version of mingw32 CRT is at least
-   maj.min
+    wxCHECK_MINGW32_VERSION() is defined in wx/msw/gccpriv.h which is included
+    later, see comments there.
  */
 
-/*
-    Define Mingw identification symbols, wxCHECK_MINGW32_VERSION() is defined in
-    wx/msw/gccpriv.h which is included later, see comments there.
- */
-#ifdef __MINGW32__
-/*
-    MinGW-w64 project provides compilers for both Win32 and Win64 but only
-    defines the same __MINGW32__ symbol for the former as MinGW32 toolchain
-    which is quite different (notably doesn't provide many SDK headers that
-    MinGW-w64 does include). So we define a separate symbol which, unlike the
-    predefined __MINGW64__, can be used to detect this toolchain in both 32 and
-    64 bit builds.
-
-    And define __MINGW32_TOOLCHAIN__ for consistency and also because it's
-    convenient as we often want to have some workarounds only for the (old)
-    MinGW32 but not (newer) MinGW-w64, which still predefines __MINGW32__.
- */
-#   ifdef __MINGW64_VERSION_MAJOR
-#       ifndef __MINGW64_TOOLCHAIN__
-#           define __MINGW64_TOOLCHAIN__
-#       endif
-#   else
-#       ifndef __MINGW32_TOOLCHAIN__
-#           define __MINGW32_TOOLCHAIN__
-#       endif
-#   endif
-#endif
-
 #endif // _WX_COMPILER_H_
diff --git a/include/wx/msw/gccpriv.h b/include/wx/msw/gccpriv.h
index 265c9048d5..4f1bc4f299 100644
--- a/include/wx/msw/gccpriv.h
+++ b/include/wx/msw/gccpriv.h
@@ -35,6 +35,28 @@
 
     #include <_mingw.h>
 
+    /*
+        MinGW-w64 project provides compilers for both Win32 and Win64 but only
+        defines the same __MINGW32__ symbol for the former as MinGW32 toolchain
+        which is quite different (notably doesn't provide many SDK headers that
+        MinGW-w64 does include). So we define a separate symbol which, unlike
+        the predefined __MINGW64__, can be used to detect this toolchain in
+        both 32 and 64 bit builds.
+
+        And define __MINGW32_TOOLCHAIN__ for consistency and also because it's
+        convenient as we often want to have some workarounds only for the (old)
+        MinGW32 but not (newer) MinGW-w64, which still predefines __MINGW32__.
+     */
+    #ifdef __MINGW64_VERSION_MAJOR
+        #ifndef __MINGW64_TOOLCHAIN__
+            #define __MINGW64_TOOLCHAIN__
+        #endif
+    #else
+        #ifndef __MINGW32_TOOLCHAIN__
+            #define __MINGW32_TOOLCHAIN__
+        #endif
+    #endif
+
     #define wxCHECK_MINGW32_VERSION( major, minor ) \
  ( ( ( __MINGW32_MAJOR_VERSION > (major) ) \
       || ( __MINGW32_MAJOR_VERSION == (major) && __MINGW32_MINOR_VERSION >= (minor) ) ) )