diff --git a/tests/hazmat/backends/test_multibackend.py b/tests/hazmat/backends/test_multibackend.py
index 3c05cdf..d516af1 100644
--- a/tests/hazmat/backends/test_multibackend.py
+++ b/tests/hazmat/backends/test_multibackend.py
@@ -206,6 +206,9 @@
     def create_x509_csr(self, builder, private_key, algorithm):
         pass
 
+    def sign_x509_certificate(self, builder, private_key, algorithm):
+        pass
+
 
 class TestMultiBackend(object):
     def test_ciphers(self):
@@ -484,6 +487,7 @@
         backend.load_pem_x509_csr(b"reqdata")
         backend.load_der_x509_csr(b"reqdata")
         backend.create_x509_csr(object(), b"privatekey", hashes.SHA1())
+        backend.sign_x509_certificate(object(), b"privatekey", hashes.SHA1())
 
         backend = MultiBackend([])
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_X509):
@@ -496,3 +500,7 @@
             backend.load_der_x509_csr(b"reqdata")
         with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_X509):
             backend.create_x509_csr(object(), b"privatekey", hashes.SHA1())
+        with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_X509):
+            backend.sign_x509_certificate(
+                object(), b"privatekey", hashes.SHA1()
+            )