diff --git a/src/if_perl.xs b/src/if_perl.xs
index 67d0b948..2655640 100644
--- a/src/if_perl.xs
+++ b/src/if_perl.xs
@@ -100,7 +100,7 @@
 
 // Work around for ActivePerl 5.20.3+: Avoid generating (g)vim.lib.
 #if defined(ACTIVEPERL_VERSION) && (ACTIVEPERL_VERSION >= 2003) \
-	&& defined(WIN32) && defined(USE_DYNAMIC_LOADING)
+	&& defined(MSWIN) && defined(USE_DYNAMIC_LOADING)
 # undef XS_EXTERNAL
 # define XS_EXTERNAL(name) XSPROTO(name)
 #endif
@@ -154,7 +154,7 @@
 #if defined(DYNAMIC_PERL) || defined(PROTO)
 
 # ifndef DYNAMIC_PERL /* just generating prototypes */
-#  ifdef WIN3264
+#  ifdef MSWIN
 typedef int HANDLE;
 #  endif
 typedef int XSINIT_t;
@@ -164,7 +164,7 @@
 typedef int perl_key;
 # endif
 
-# ifndef WIN3264
+# ifndef MSWIN
 #  include <dlfcn.h>
 #  define HANDLE void*
 #  define PERL_PROC void*