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.