diff --git a/.code-spell-ignore b/.code-spell-ignore
index fc981f07c..0132a2c6d 100644
--- a/.code-spell-ignore
+++ b/.code-spell-ignore
@@ -1,6 +1,7 @@
 aanother
 acount
 addrss
+afile
 aline
 anumber
 ans
diff --git a/tests/scripts/thread-cert/coap.py b/tests/scripts/thread-cert/coap.py
index 6fec6f2ef..337e91c1c 100644
--- a/tests/scripts/thread-cert/coap.py
+++ b/tests/scripts/thread-cert/coap.py
@@ -61,7 +61,7 @@ class CoapOptionsTypes(IntEnum):
 
 
 class CoapOptionHeader(object):
-    """ Class representing CoAP optiona header. """
+    """ Class representing CoAP optional header. """
 
     def __init__(self, delta, length):
         self._delta = delta