diff --git a/android_env/components/coordinator.py b/android_env/components/coordinator.py
index c309239..319fb6d 100644
--- a/android_env/components/coordinator.py
+++ b/android_env/components/coordinator.py
@@ -362,6 +362,7 @@ def _gather_simulator_signals(self) -> dict[str, np.ndarray]:
 
     # Grab pixels.
     if self._interaction_rate_sec > 0:
+      assert self._interaction_thread is not None
       pixels = self._interaction_thread.screenshot()  # Async mode.
     else:
       pixels = self._simulator.get_screenshot()  # Sync mode.