diff --git a/dtool/src/dtoolbase/dtoolbase.h b/dtool/src/dtoolbase/dtoolbase.h
index ae74fd644f..a3cb5f0614 100644
--- a/dtool/src/dtoolbase/dtoolbase.h
+++ b/dtool/src/dtoolbase/dtoolbase.h
@@ -332,7 +332,7 @@ typedef struct _object PyObject;
 
 #ifdef __WORDSIZE
 #define NATIVE_WORDSIZE __WORDSIZE
-#elif defined(_LP64)
+#elif defined(_LP64) || defined(_WIN64)
 #define NATIVE_WORDSIZE 64
 #else
 #define NATIVE_WORDSIZE 32