diff --git a/src/common/state_machine.hpp b/src/common/state_machine.hpp
index 15dbce29b..78ff58c2f 100644
--- a/src/common/state_machine.hpp
+++ b/src/common/state_machine.hpp
@@ -223,6 +223,21 @@ class StateMachineRunner : virtual public EventPoster<EventType> {
 			// actionable until at least one state machine reaches a different state.
 			PostToEventLoop();
 		}
+
+		// Check if there are any non-deferred events in the queue - then fail if
+		queue<EventType> queue_copy = event_queue_;
+		while (not queue_copy.empty()) {
+			// If we have no more states, but there is still an event left in the
+			// queue which is not deferred, then we have a serious logic problem. Panic!
+			EventType event = queue_copy.front();
+			queue_copy.pop();
+			for (auto machine : machines_) {
+				if (machine->deferred_events_.find(event) == machine->deferred_events_.end()) {
+					log::Fatal(
+						"The state machine has an unprocessed non-deferred event in the queue. This is a programming error!");
+				}
+			}
+		}
 	}
 
 	void PostToEventLoop() {