diff --git a/include/sxt/errno.h b/include/sxt/errno.h
index 21cd610..0f6f7a9 100644
--- a/include/sxt/errno.h
+++ b/include/sxt/errno.h
@@ -45,6 +45,7 @@
 #define SXT_EKEY            (SXT_EBASESHIFT + 14)
 #define SXT_EHASH           (SXT_EBASESHIFT + 15)
 #define SXT_ERDBRD          (SXT_EBASESHIFT + 16)
+#define SXT_EIO             (SXT_EBASESHIFT + 17)
 #define SXT_EINVAL          (SXT_EBASESHIFT + 22)
 #define SXT_ENOMEM          (SXT_EBASESHIFT + 42)