1 files changed, 1 insertions, 0 deletions
diff --git a/io.c b/io.c
index 982e83e5cc..716bc6d506 100644
--- a/io.c
+++ b/io.c
@@ -15,6 +15,7 @@
 #include "ruby/io.h"
 #include "ruby/thread.h"
 #include "dln.h"
+#include "encindex.h"
 #include "id.h"
 #include <ctype.h>
 #include <errno.h>