diff --git a/Makefile b/Makefile
index 7b540d5..3611457 100644
--- a/Makefile
+++ b/Makefile
@@ -5,7 +5,7 @@
 PROJECT=github.com/takama/backer
 
 # Use the 0.0.0 tag for testing, it shouldn't clobber any release builds
-RELEASE?=v0.3.9
+RELEASE?=v0.4.0
 
 BUILDTAGS=
 
diff --git a/tournament/tournament.go b/tournament/tournament.go
index 3d7b2f3..4cc2cc5 100644
--- a/tournament/tournament.go
+++ b/tournament/tournament.go
@@ -145,6 +145,7 @@ func (entry *Entry) Join(players ...backer.Player) error {
 	}
 
 	var bidder model.Bidder
+	bidder.Backers = make([]string, 0)
 	contribute := float32(tournament.Deposit / backer.Points(len(players)))
 	for idx, participant := range players {
 		if _, err := player.ManagePoints(entry.Controller, tx,