diff --git a/cylc/flow/cycling/iso8601.py b/cylc/flow/cycling/iso8601.py
index de180b5390a..ed5b4f21979 100644
--- a/cylc/flow/cycling/iso8601.py
+++ b/cylc/flow/cycling/iso8601.py
@@ -294,7 +294,7 @@ class ISO8601Sequence(SequenceBase):
 
     Args:
         dep_section:
-            The full sequence expresion.
+            The full sequence expression.
         context_start_point:
             Sequence start point from the global context.
         context_end_point: