1 files changed, 1 insertions, 0 deletions

diff --git a/io.c b/io.c
index 2eba0ec6d4..30150fc507 100644
--- a/io.c
+++ b/io.c
@@ -507,6 +507,7 @@ ruby_dup(int orig)
 	    rb_sys_fail(0);
 	}
     }
+    UPDATE_MAXFD(fd);
     return fd;
 }