diff --git a/src/mclean_extreme.c b/src/mclean_extreme.c
index 5785a24..5c8060c 100644
--- a/src/mclean_extreme.c
+++ b/src/mclean_extreme.c
@@ -420,6 +420,10 @@ mclean_extreme_device_open(dc_device_t **out, dc_context_t *context, dc_iostream
 		goto error_free;
 	}
 
+	// Make sure everything is in a sane state.
+	dc_iostream_sleep (device->iostream, 100);
+	dc_iostream_purge (device->iostream, DC_DIRECTION_ALL);
+
 	*out = (dc_device_t *)device;
 
 	return DC_STATUS_SUCCESS;
diff --git a/src/tecdiving_divecomputereu.c b/src/tecdiving_divecomputereu.c
index cf88b30..93190e2 100644
--- a/src/tecdiving_divecomputereu.c
+++ b/src/tecdiving_divecomputereu.c
@@ -376,6 +376,10 @@ tecdiving_divecomputereu_device_open (dc_device_t **out, dc_context_t *context,
 		goto error_free;
 	}
 
+	// Make sure everything is in a sane state.
+	dc_iostream_sleep (device->iostream, 100);
+	dc_iostream_purge (device->iostream, DC_DIRECTION_ALL);
+
 	// Send the init command.
 	status = tecdiving_divecomputereu_send (device, CMD_INIT, NULL, 0);
 	if (status != DC_STATUS_SUCCESS) {