diff --git a/reactos/tools/mkhive/mkhive.c b/reactos/tools/mkhive/mkhive.c
index 360021e9030..a7f99f49471 100644
--- a/reactos/tools/mkhive/mkhive.c
+++ b/reactos/tools/mkhive/mkhive.c
@@ -35,7 +35,7 @@
 #define PATH_MAX _MAX_PATH
 #endif//_MSC_VER
 
-#ifndef WIN32
+#ifndef WINDOWS_HOST
 #ifndef PATH_MAX
 #define PATH_MAX 260
 #endif
@@ -62,7 +62,7 @@ void convert_path(char *dst, char *src)
   i = 0;
   while (src[i] != 0)
     {
-#ifdef WIN32
+#ifdef WINDOWS_HOST
       if (src[i] == '/')
 	{
 	  dst[i] = '\\';
diff --git a/reactos/tools/mkhive/mkhive.h b/reactos/tools/mkhive/mkhive.h
index 50161404ef8..bb7da55512c 100644
--- a/reactos/tools/mkhive/mkhive.h
+++ b/reactos/tools/mkhive/mkhive.h
@@ -29,6 +29,11 @@
 
 #include <stdio.h>
 
+/* We have to do this because psdk/windef.h will _always_ define _WIN32... */
+#if defined(_WIN32) || defined(_WIN64)
+#define WINDOWS_HOST
+#endif
+
 #define NTOS_MODE_USER
 #define WIN32_NO_STATUS
 #include <ntddk.h>
@@ -76,7 +81,7 @@ static void DPRINT ( const char* fmt, ... )
 
 #define CHECKPOINT
 
-#ifdef _WIN32
+#ifdef WINDOWS_HOST
 #define strncasecmp _strnicmp
 #define strcasecmp _stricmp
 #else