Fixed misspelling
diff --git a/docs/hazmat/primitives/key-derivation-functions.rst b/docs/hazmat/primitives/key-derivation-functions.rst
index 269f949..ee8f8ab 100644
--- a/docs/hazmat/primitives/key-derivation-functions.rst
+++ b/docs/hazmat/primitives/key-derivation-functions.rst
@@ -194,7 +194,7 @@
     .. method:: derive(key_material)
 
         :param bytes key_material: The input key material.
-        :retunr bytes: The derived key.
+        :return bytes: The derived key.
 
         Derives a new key from the input key material by performing both the
         extract and expand operations.