diff --git a/docs/05-command-line.md b/docs/05-command-line.md
index c3a2d7994..e805bf2e7 100644
--- a/docs/05-command-line.md
+++ b/docs/05-command-line.md
@@ -13,7 +13,7 @@ $ npx ava --help
     --match, -m             Only run tests with matching title (Can be repeated)
     --update-snapshots, -u  Update snapshots
     --fail-fast             Stop after first test failure
-    --timeout, -T           Set global timeout
+    --timeout, -T           Set global timeout (milliseconds or human-readable, e.g. 10s, 2m)
     --serial, -s            Run tests serially
     --concurrency, -c       Max number of test files running at the same time (Default: CPU cores)
     --verbose, -v           Enable verbose output
diff --git a/lib/cli.js b/lib/cli.js
index de2946049..f94aa34da 100644
--- a/lib/cli.js
+++ b/lib/cli.js
@@ -35,7 +35,7 @@ exports.run = async () => { // eslint-disable-line complexity
 		  --match, -m             Only run tests with matching title (Can be repeated)
 		  --update-snapshots, -u  Update snapshots
 		  --fail-fast             Stop after first test failure
-		  --timeout, -T           Set global timeout
+		  --timeout, -T           Set global timeout (milliseconds or human-readable, e.g. 10s, 2m)
 		  --serial, -s            Run tests serially
 		  --concurrency, -c       Max number of test files running at the same time (Default: CPU cores)
 		  --verbose, -v           Enable verbose output