diff --git a/Server/src/main/kotlin/rs09/game/world/PulseRunner.kt b/Server/src/main/kotlin/rs09/game/world/PulseRunner.kt
index 143986e89..67c00794f 100644
--- a/Server/src/main/kotlin/rs09/game/world/PulseRunner.kt
+++ b/Server/src/main/kotlin/rs09/game/world/PulseRunner.kt
@@ -10,8 +10,11 @@ import java.util.*
 
 class PulseRunner {
     val TASKS = ArrayList<Pulse>()
+
     fun submit(pulse: Pulse){
-        TASKS.add(pulse)
+        synchronized(this.TASKS) {
+            TASKS.add(pulse)
+        }
     }
 }
 /*
diff --git a/Server/src/main/kotlin/rs09/worker/MajorUpdateWorker.kt b/Server/src/main/kotlin/rs09/worker/MajorUpdateWorker.kt
index 438c9223d..6a3728878 100644
--- a/Server/src/main/kotlin/rs09/worker/MajorUpdateWorker.kt
+++ b/Server/src/main/kotlin/rs09/worker/MajorUpdateWorker.kt
@@ -106,7 +106,9 @@ class MajorUpdateWorker {
 
         //remove all null or finished pulses from the list
         rmlist.forEach {
-            GameWorld.Pulser.TASKS.remove(it)
+            synchronized(GameWorld.Pulser.TASKS) {
+                GameWorld.Pulser.TASKS.remove(it)
+            }
         }
 
         rmlist.clear()