diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index 94a81ce..4851dfc 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -61,7 +61,8 @@
     def serial(self):
         warnings.warn(
             "Certificate serial is deprecated, use serial_number instead.",
-            utils.DeprecatedIn10
+            utils.DeprecatedIn14,
+            stacklevel=2
         )
         return self.serial_number
 
diff --git a/src/cryptography/x509/base.py b/src/cryptography/x509/base.py
index 8e3f966..ab70fe7 100644
--- a/src/cryptography/x509/base.py
+++ b/src/cryptography/x509/base.py
@@ -63,12 +63,6 @@
         """
 
     @abc.abstractproperty
-    def serial(self):
-        """
-        Returns certificate serial number
-        """
-
-    @abc.abstractproperty
     def serial_number(self):
         """
         Returns certificate serial number