diff --git a/application/src/main/java/org/thingsboard/server/service/subscription/TbAlarmDataSubCtx.java b/application/src/main/java/org/thingsboard/server/service/subscription/TbAlarmDataSubCtx.java
index d6a7abc063..1f7ab2a04b 100644
--- a/application/src/main/java/org/thingsboard/server/service/subscription/TbAlarmDataSubCtx.java
+++ b/application/src/main/java/org/thingsboard/server/service/subscription/TbAlarmDataSubCtx.java
@@ -128,7 +128,7 @@ public class TbAlarmDataSubCtx extends TbAbstractDataSubCtx<AlarmDataQuery> {
             }
         }
         alarmsMap.clear();
-        alarmsMap.putAll(alarms.getData().stream().collect(Collectors.toMap(AlarmData::getId, Function.identity())));
+        alarmsMap.putAll(alarms.getData().stream().collect(Collectors.toMap(AlarmData::getId, Function.identity(), (a, b) -> a)));
         return this.alarms;
     }