diff --git a/src/core/buffer.c b/src/core/buffer.c
index 51e5dfeb..6e05b088 100644
--- a/src/core/buffer.c
+++ b/src/core/buffer.c
@@ -93,6 +93,7 @@
 #include "stddef.h"
 #include "string.h"
 #include "io.h"
+#include "errno.h"
 #include "buffer.h"
 
 /**