diff --git a/src/db/dbEvent.c b/src/db/dbEvent.c
index ee1673547..80a28add9 100644
--- a/src/db/dbEvent.c
+++ b/src/db/dbEvent.c
@@ -964,6 +964,7 @@ static void event_task (void *pParm)
     } while( ! pendexit );
 
     epicsMutexDestroy(evUser->firstque.writelock);
+    evUser->firstque.writelock = (epicsMutexId)0xdeadbeef;
 
     {
         struct event_que    *nextque;
@@ -972,6 +973,7 @@ static void event_task (void *pParm)
         while(ev_que){ 
             nextque = ev_que->nextque;
             epicsMutexDestroy(ev_que->writelock);
+            ev_que->writelock = (epicsMutexId)0xdeadbeef;
             freeListFree(dbevEventQueueFreeList, ev_que);
             ev_que = nextque;
         }
@@ -980,6 +982,7 @@ static void event_task (void *pParm)
     epicsEventDestroy(evUser->ppendsem);
     epicsEventDestroy(evUser->pflush_sem);
     epicsMutexDestroy(evUser->lock);
+    evUser->lock = (epicsMutexId)0xdeadbeef;
 
     freeListFree(dbevEventUserFreeList, evUser);