diff --git a/src/cryptography/utils.py b/src/cryptography/utils.py
index 4ca4a7a..993571b 100644
--- a/src/cryptography/utils.py
+++ b/src/cryptography/utils.py
@@ -47,16 +47,10 @@
         return result
 
 
-if hasattr(int, "to_bytes"):
-    int_to_bytes = int.to_bytes
-else:
-    def int_to_bytes(integer, byteorder, signed=False):
-        assert byteorder == 'big'
-        assert not signed
-
-        hex_string = '%x' % integer
-        n = len(hex_string)
-        return binascii.unhexlify(hex_string.zfill(n + (n & 1)))
+def int_to_bytes(integer):
+    hex_string = '%x' % integer
+    n = len(hex_string)
+    return binascii.unhexlify(hex_string.zfill(n + (n & 1)))
 
 
 class InterfaceNotImplemented(Exception):
diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index 3254f26..82b8bd3 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -698,7 +698,7 @@
         for bit in spki.getComponentByName("subjectPublicKey"):
             bits = bits << 1 | bit
 
-        data = utils.int_to_bytes(bits, "big")
+        data = utils.int_to_bytes(bits)
         return cls(hashlib.sha1(data).digest())
 
     digest = utils.read_only_property("_digest")