diff --git a/cryptography/hazmat/primitives/interfaces.py b/cryptography/hazmat/primitives/interfaces.py
index da4fa20..67dbe6f 100644
--- a/cryptography/hazmat/primitives/interfaces.py
+++ b/cryptography/hazmat/primitives/interfaces.py
@@ -37,7 +37,7 @@
     @abc.abstractproperty
     def initialization_vector(self):
         """
-        The value of the initialization vector for this mode.
+        The value of the initialization vector for this mode as bytes.
         """
 
 
@@ -45,7 +45,7 @@
     @abc.abstractproperty
     def nonce(self):
         """
-        The value of the nonce for this mode.
+        The value of the nonce for this mode as bytes.
         """