diff --git a/acme/api/handler_test.go b/acme/api/handler_test.go
index d1e6a719..9b8d0491 100644
--- a/acme/api/handler_test.go
+++ b/acme/api/handler_test.go
@@ -41,7 +41,6 @@ type mockAcmeAuthority struct {
 	updateAccount       func(provisioner.Interface, string, []string) (*acme.Account, error)
 	useNonce            func(string) error
 	validateChallenge   func(p provisioner.Interface, accID string, id string, jwk *jose.JSONWebKey) (*acme.Challenge, error)
-	backoffChallenge    func(p provisioner.Interface, accID, chID string, jwk *jose.JSONWebKey) (time.Duration, error)
 	ret1                interface{}
 	err                 error
 }
@@ -204,17 +203,6 @@ func (m *mockAcmeAuthority) ValidateChallenge(p provisioner.Interface, accID str
 	}
 }
 
-func (m *mockAcmeAuthority) BackoffChallenge(p provisioner.Interface, accID, chID string, jwk *jose.JSONWebKey) (time.Duration, error) {
-	switch {
-	case m.backoffChallenge != nil:
-		return m.backoffChallenge(p, accID, chID, jwk)
-	case m.err != nil:
-		return -1, m.err
-	default:
-		return m.ret1.(time.Duration), m.err
-	}
-}
-
 func TestHandlerGetNonce(t *testing.T) {
 	tests := []struct {
 		name       string
@@ -807,7 +795,7 @@ func TestHandlerGetChallenge(t *testing.T) {
 				case "processing":
 					assert.Equals(t, res.Header["Cache-Control"], []string{"no-cache"})
 					assert.Equals(t, res.Header["Retry-After"], []string{tc.ch.RetryAfter})
-				case "valid":
+				case "valid", "invalid":
 					assert.Equals(t, res.Header["Location"], []string{url})
 					assert.Equals(t, res.Header["Link"], []string{fmt.Sprintf("<https://ca.smallstep.com/acme/authz/%s>;rel=\"up\"", tc.ch.AuthzID)})
 				}