diff --git a/ssh/agent/keyring.go b/ssh/agent/keyring.go
index 831a5b9..8ac2009 100644
--- a/ssh/agent/keyring.go
+++ b/ssh/agent/keyring.go
@@ -175,7 +175,7 @@ func (r *keyring) Signers() ([]ssh.Signer, error) {
 		return nil, errLocked
 	}
 
-	s := make([]ssh.Signer, len(r.keys))
+	s := make([]ssh.Signer, 0, len(r.keys))
 	for _, k := range r.keys {
 		s = append(s, k.signer)
 	}