diff --git a/code/controllers/subsystem/timer.dm b/code/controllers/subsystem/timer.dm
index ee68573fc63..8ca3ee76f9b 100644
--- a/code/controllers/subsystem/timer.dm
+++ b/code/controllers/subsystem/timer.dm
@@ -127,7 +127,9 @@ SUBSYSTEM_DEF(timer)
 		ctime_timer.spent = REALTIMEOFDAY
 		callBack.InvokeAsync()
 
-		if(ctime_timer.flags & TIMER_LOOP)
+		if(ctime_timer.flags & TIMER_LOOP) // Re-insert valid looping client timers into the client timer list.
+			if (QDELETED(ctime_timer)) // Don't re-insert timers deleted inside their callbacks.
+				continue
 			ctime_timer.spent = 0
 			ctime_timer.timeToRun = REALTIMEOFDAY + ctime_timer.wait
 			BINARY_INSERT(ctime_timer, clienttime_timers, /datum/timedevent, ctime_timer, timeToRun, COMPARE_KEY)
@@ -173,7 +175,9 @@ SUBSYSTEM_DEF(timer)
 				callBack.InvokeAsync()
 				last_invoke_tick = world.time
 
-			if (timer.flags & TIMER_LOOP) // Prepare looping timers to re-enter the queue
+			if (timer.flags & TIMER_LOOP) // Prepare valid looping timers to re-enter the queue
+				if(QDELETED(timer)) // If a loop is deleted in its callback, we need to avoid re-inserting it.
+					continue
 				timer.spent = 0
 				timer.timeToRun = world.time + timer.wait
 				timer.bucketJoin()