diff --git a/README.md b/README.md
index 7de48be..5070a1a 100644
--- a/README.md
+++ b/README.md
@@ -97,7 +97,8 @@ obs = sim.read_bodies(stream=stream)  # sync already done, just read pinned buff
 `FixedPatchStepper` advances one fixed 2:1 refinement patch inside a coarse
 grid, optionally with stationary circles in the fine region and a prescribed
 normal surface velocity (blowing/suction). It is a standalone backend, not part
-of `Simulation`. Runnable demo: `examples/fixed_patch_circle.py`.
+of `Simulation`. Runnable demo (blocked fine storage; omit `--fine-block`
+for dense): `PYTHONPATH="$PWD/src" python examples/fixed_patch_circle.py --fine-block 16 20`.
 
 ```python
 import numpy as np