diff --git a/error.go b/error.go
index 01a21e9..a30d986 100644
--- a/error.go
+++ b/error.go
@@ -12,6 +12,7 @@ type Error string; const (
 	ErrPathNotAbsolute      Error = "path is not absolute"
 	ErrInsufficientSystem   Error = "the system cannot perform this action"
 	ErrPigsFlying           Error = "play the lottery today"
+	ErrDoubleClose          Error = "object was closed twice"
 )
 
 // Error fulfills the error interface.