diff --git a/src/uvwasi.c b/src/uvwasi.c
index 28c6dcc..1f80fb8 100644
--- a/src/uvwasi.c
+++ b/src/uvwasi.c
@@ -11,6 +11,7 @@
 # define SLASH_STR "/"
 # define IS_SLASH(c) ((c) == '/')
 #else
+# include <io.h>
 # define SLASH '\\'
 # define SLASH_STR "\\"
 # define IS_SLASH(c) ((c) == '/' || (c) == '\\')