diff --git a/boards/chronos/stdio.c b/boards/chronos/stdio.c
index d7e9ceb3cb..a6def45cb9 100644
--- a/boards/chronos/stdio.c
+++ b/boards/chronos/stdio.c
@@ -40,3 +40,8 @@ int getchar(void)
     /* dummy implementation */
     return EOF;
 }
+
+ssize_t write(int fildes, const void *buf, size_t nbyte)
+{
+    return -1;
+}