diff --git a/git.go b/git.go
index 4f1a65e..a44459f 100644
--- a/git.go
+++ b/git.go
@@ -87,6 +87,8 @@ const (
 	ErrPassthrough ErrorCode = C.GIT_PASSTHROUGH
 	// Signals end of iteration with iterator
 	ErrIterOver ErrorCode = C.GIT_ITEROVER
+	// Authentication failed
+	ErrAuth ErrorCode = C.GIT_EAUTH
 )
 
 var (