diff --git a/numpy/core/src/multiarray/convert.c b/numpy/core/src/multiarray/convert.c
index aef78ff5ef23..60c1a1b9b011 100644
--- a/numpy/core/src/multiarray/convert.c
+++ b/numpy/core/src/multiarray/convert.c
@@ -157,7 +157,7 @@ PyArray_ToFile(PyArrayObject *self, FILE *fp, char *sep, char *format)
             size = PyArray_SIZE(self);
             NPY_BEGIN_ALLOW_THREADS;
 
-#if defined(NPY_OS_WIN64)
+#if defined(_WIN64)
             /*
              * Workaround Win64 fwrite() bug. Issue gh-2256
              * The native 64 windows runtime has this issue, the above will