diff --git a/core/flash.cpp b/core/flash.cpp
index 066a6b1..4d67cd9 100644
--- a/core/flash.cpp
+++ b/core/flash.cpp
@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>