diff --git a/src/core/ev.c b/src/core/ev.c
index 93cc8679..3d4964e8 100644
--- a/src/core/ev.c
+++ b/src/core/ev.c
@@ -35,6 +35,7 @@
 #ifdef JANET_WINDOWS
 #include <winsock2.h>
 #include <windows.h>
+#include <io.h>
 #else
 #include <pthread.h>
 #include <limits.h>