diff --git a/src/core/io.c b/src/core/io.c
index cb089adb..f941733d 100644
--- a/src/core/io.c
+++ b/src/core/io.c
@@ -285,6 +285,7 @@ static Janet cfun_io_fclose(int32_t argc, Janet *argv) {
     if (iof->flags & IO_PIPED) {
 #ifdef JANET_WINDOWS
 #define pclose _pclose
+#define WEXITSTATUS(x) x
 #endif
         int status = pclose(iof->file);
         iof->flags |= IO_CLOSED;