diff --git a/src/rabit.h b/src/rabit.h
index f19792442..c7cde6b4b 100644
--- a/src/rabit.h
+++ b/src/rabit.h
@@ -10,6 +10,7 @@
  */
 #include <string>
 #include <vector>
+#include "./io.h"
 #include "./engine.h"
 
 /*! \brief namespace of rabit */