diff --git a/tests/timeline.md b/tests/timeline.md
index 8b77e30e..eedafd79 100644
--- a/tests/timeline.md
+++ b/tests/timeline.md
@@ -43,7 +43,7 @@ A *timeline* is a sequence of [occurrences](#Occurrence), in order in which they
 
 A timeline can be grown by recording new occurrences in it. This is done automatically by the test infrastructure for requests, responses and events occurring in a debug session. Marks are recorded with the `timeline.mark(id)` method, which returns the recorded mark occurrence. It is not possible to "rewrite the history" - once recorded, occurrences can never be forgotten, and do not change.
 
-Timelines are completely thread-safe for both recording and inspection. However, because a timeline during an active debug session can grow asyncronously as new events and responses are received, it cannot be inspected directly, other than asking for the last occurrence via `timeline.last()` - which is a function rather than a property, indicating that it may return a different value on every subsequent call.
+Timelines are completely thread-safe for both recording and inspection. However, because a timeline during an active debug session can grow asynchronously as new events and responses are received, it cannot be inspected directly, other than asking for the last occurrence via `timeline.last()` - which is a function rather than a property, indicating that it may return a different value on every subsequent call.
 
 It is, however, possible to take a snapshot of a timeline via `timeline.history()`; the returned value is a list of all occurrences that were in the timeline at the point of the call, in order from first to last. This is just a shortcut for `reversed(list(timeline.last()))`.