diff --git a/lib/System/Win32/DynamicLibrary.inc b/lib/System/Win32/DynamicLibrary.inc
index af28f75..2209e59 100644
--- a/lib/System/Win32/DynamicLibrary.inc
+++ b/lib/System/Win32/DynamicLibrary.inc
@@ -13,7 +13,7 @@
 
 #include "Win32.h"
 
-#ifdef __MINGW
+#ifdef __MINGW32__
 #include <imagehlp.h>
 #else
 #include <dbghelp.h>
diff --git a/lib/System/Win32/Process.inc b/lib/System/Win32/Process.inc
index 7c8de64..a47ff2e 100644
--- a/lib/System/Win32/Process.inc
+++ b/lib/System/Win32/Process.inc
@@ -23,7 +23,7 @@
 //===          and must not be UNIX code
 //===----------------------------------------------------------------------===//
 
-#ifdef __MINGW
+#ifdef __MINGW32__
 // This ban should be lifted when MinGW 1.0+ has defined this value.
 #  define _HEAPOK (-2)
 #endif
diff --git a/lib/System/Win32/Signals.inc b/lib/System/Win32/Signals.inc
index afe6c8d..55e2d2d 100644
--- a/lib/System/Win32/Signals.inc
+++ b/lib/System/Win32/Signals.inc
@@ -15,7 +15,7 @@
 #include <stdio.h>
 #include <vector>
 
-#ifdef __MINGW
+#ifdef __MINGW32__
 #include <imagehlp.h>
 #else
 #include <dbghelp.h>
diff --git a/lib/System/Win32/TimeValue.inc b/lib/System/Win32/TimeValue.inc
index 34a5df1..01f7484 100644
--- a/lib/System/Win32/TimeValue.inc
+++ b/lib/System/Win32/TimeValue.inc
@@ -31,7 +31,7 @@
 }
 
 std::string TimeValue::toString() const {
-#ifdef __MINGW
+#ifdef __MINGW32__
   // This ban may be lifted by either:
   // (i) a future MinGW version other than 1.0 inherents the __time64_t type, or
   // (ii) configure tests for either the time_t or __time64_t type.