diff --git a/src/hardware/demo/demo.c b/src/hardware/demo/demo.c
index 1b258727..6042cfd9 100644
--- a/src/hardware/demo/demo.c
+++ b/src/hardware/demo/demo.c
@@ -784,8 +784,8 @@ static int prepare_data(int fd, int revents, void *cb_data)
 	 */
 	todo_us = samples_todo * G_USEC_PER_SEC / devc->cur_samplerate;
 
-	logic_done = 0;
-	analog_done = 0;
+	logic_done  = devc->num_logic_channels  > 0 ? 0 : samples_todo;
+	analog_done = devc->num_analog_channels > 0 ? 0 : samples_todo;
 
 	while (logic_done < samples_todo || analog_done < samples_todo) {
 		/* Logic */