1 files changed, 1 insertions, 0 deletions
diff --git a/debug.c b/debug.c
index f811ec6779..e4ad163ad1 100644
--- a/debug.c
+++ b/debug.c
@@ -11,6 +11,7 @@
 
 #include "ruby/ruby.h"
 #include "ruby/encoding.h"
+#include "ruby/io.h"
 #include "ruby/util.h"
 #include "vm_debug.h"
 #include "eval_intern.h"