diff --git a/src/main/java/org/runejs/client/media/renderable/actor/Npc.java b/src/main/java/org/runejs/client/media/renderable/actor/Npc.java
index 4e6d241f7..28c668273 100644
--- a/src/main/java/org/runejs/client/media/renderable/actor/Npc.java
+++ b/src/main/java/org/runejs/client/media/renderable/actor/Npc.java
@@ -11,49 +11,117 @@ public class Npc extends Actor {
     public ActorDefinition actorDefinition;
 
     public static void parseNpcUpdateMasks(PacketBuffer buffer) {
-        for(int i = 0; i < actorUpdatingIndex; i++) {
-            int npcIndex = Player.actorUpdatingIndices[i];
-            Npc npc = Player.npcs[npcIndex];
+        for (int i = 0; i < actorUpdatingIndex; i++) {
+            int npcIndex = -1;
+            Npc npc = null;
+
+            boolean alreadyGotWorldIndex = false;
+
             int mask = buffer.getUnsignedByte();
-            if((0x1 & mask) != 0) {
+            if ((0x1 & mask) != 0) {
                 int i_3_ = buffer.getUnsignedByte();
                 int i_4_ = buffer.getUnsignedByte();
+                int remainingHitpoints = buffer.getUnsignedByte();
+                int maximumHitpoints = buffer.getUnsignedByte();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
                 npc.method785(i_4_, MovedStatics.pulseCycle, i_3_);
                 npc.anInt3139 = MovedStatics.pulseCycle + 300;
-                npc.remainingHitpoints = buffer.getUnsignedByte();
-                npc.maximumHitpoints = buffer.getUnsignedByte();
+                npc.remainingHitpoints = remainingHitpoints;
+                npc.maximumHitpoints = maximumHitpoints;
             }
-            if((0x20 & mask) != 0) {
-                npc.graphicId = buffer.getUnsignedShortLE();
+            if ((0x20 & mask) != 0) {
+                int graphicId = buffer.getUnsignedShortLE();
                 int i_5_ = buffer.getIntBE();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+                npc.graphicId = graphicId;
                 npc.anInt3129 = 0;
                 npc.graphicDelay = MovedStatics.pulseCycle + (0xffff & i_5_);
                 npc.graphicHeight = i_5_ >> 16;
                 npc.anInt3140 = 0;
-                if(npc.graphicDelay > MovedStatics.pulseCycle)
+                if (npc.graphicDelay > MovedStatics.pulseCycle)
                     npc.anInt3140 = -1;
-                if(npc.graphicId == 65535)
+                if (npc.graphicId == 65535)
                     npc.graphicId = -1;
             }
-            if((mask & 0x4) != 0) {
-                npc.facingActorIndex = buffer.getUnsignedShortBE();
-                if(npc.facingActorIndex == 65535)
+            if ((mask & 0x4) != 0) {
+                int facingActorIndex = buffer.getUnsignedShortBE();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
+                npc.facingActorIndex = facingActorIndex;
+
+                if (npc.facingActorIndex == 65535)
                     npc.facingActorIndex = -1;
             }
-            if((0x2 & mask) != 0) {
+            if ((0x2 & mask) != 0) {
                 int i_6_ = buffer.getUnsignedByte();
                 int i_7_ = buffer.getUnsignedByte();
+
+                int remainingHitpoints = buffer.getUnsignedByte();
+                int maximumHitpoints = buffer.getUnsignedByte();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
                 npc.method785(i_7_, MovedStatics.pulseCycle, i_6_);
                 npc.anInt3139 = MovedStatics.pulseCycle + 300;
-                npc.remainingHitpoints = buffer.getUnsignedByte();
-                npc.maximumHitpoints = buffer.getUnsignedByte();
+
+                npc.remainingHitpoints = remainingHitpoints;
+                npc.maximumHitpoints = maximumHitpoints;
             }
-            if((0x40 & mask) != 0) {
-                npc.forcedChatMessage = buffer.getString();
+            if ((0x40 & mask) != 0) {
+                String forcedChatMessage = buffer.getString();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
+                npc.forcedChatMessage = forcedChatMessage;
+
                 npc.chatTimer = 100;
             }
-            if((mask & 0x80) != 0) {
-                npc.actorDefinition = ActorDefinition.getDefinition(buffer.getUnsignedShortBE());
+            if ((mask & 0x80) != 0) {
+                int actorDefinition = buffer.getUnsignedShortBE();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
+                npc.actorDefinition = ActorDefinition.getDefinition(actorDefinition);
                 npc.anInt3083 = npc.actorDefinition.rotateRightAnimation;
                 npc.anInt3113 = npc.actorDefinition.degreesToTurn;
                 npc.turnRightAnimationId = npc.actorDefinition.rotate90RightAnimation;
@@ -64,26 +132,50 @@ public static void parseNpcUpdateMasks(PacketBuffer buffer) {
                 npc.turnLeftAnimationId = npc.actorDefinition.rotate90LeftAnimation;
                 npc.turnAroundAnimationId = npc.actorDefinition.rotate180Animation;
             }
-            if((mask & 0x8) != 0) {
-                npc.facePositionX = buffer.getUnsignedShortBE();
-                npc.facePositionY = buffer.getUnsignedShortLE();
+            if ((mask & 0x8) != 0) {
+                int facePositionX = buffer.getUnsignedShortBE();
+                int facePositionY = buffer.getUnsignedShortLE();
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
+                npc.facePositionX = facePositionX;
+                npc.facePositionY = facePositionY;
             }
-            if((0x10 & mask) != 0) {
+            if ((0x10 & mask) != 0) {
                 int animationId = buffer.getUnsignedShortBE();
-                if(animationId == 65535)
-                    animationId = -1;
                 int animationDelay = buffer.getUnsignedByte();
-                if(animationId == npc.playingAnimation && animationId != -1) {
+
+                // the NPC's worldIndex bytes won't be included if already
+                // sent earlier
+                if (!alreadyGotWorldIndex) {
+                    npcIndex = buffer.getUnsignedShortBE();
+                    npc = Player.npcs[npcIndex];
+                    alreadyGotWorldIndex = true;
+                }
+
+                if (animationId == 65535) {
+                    animationId = -1;
+                }
+
+                if (animationId == npc.playingAnimation && animationId != -1) {
                     int i_10_ = AnimationSequence.getAnimationSequence(animationId).replyMode;
-                    if(i_10_ == 1) {
+                    if (i_10_ == 1) {
                         npc.anInt3115 = 0;
                         npc.anInt3095 = 0;
                         npc.anInt3104 = 0;
                         npc.playingAnimationDelay = animationDelay;
                     }
-                    if(i_10_ == 2)
+                    if (i_10_ == 2)
                         npc.anInt3095 = 0;
-                } else if(animationId == -1 || npc.playingAnimation == -1 || AnimationSequence.getAnimationSequence(animationId).forcedPriority >= AnimationSequence.getAnimationSequence(npc.playingAnimation).forcedPriority) {
+                } else if (animationId == -1 || npc.playingAnimation == -1
+                        || AnimationSequence.getAnimationSequence(animationId).forcedPriority >= AnimationSequence
+                                .getAnimationSequence(npc.playingAnimation).forcedPriority) {
                     npc.playingAnimation = animationId;
                     npc.anInt3115 = 0;
                     npc.playingAnimationDelay = animationDelay;
diff --git a/src/main/java/org/runejs/client/message/handler/rs435/updating/UpdateNPCsMessageHandler.java b/src/main/java/org/runejs/client/message/handler/rs435/updating/UpdateNPCsMessageHandler.java
index 64dcc7d4c..2c2830bd4 100644
--- a/src/main/java/org/runejs/client/message/handler/rs435/updating/UpdateNPCsMessageHandler.java
+++ b/src/main/java/org/runejs/client/message/handler/rs435/updating/UpdateNPCsMessageHandler.java
@@ -24,9 +24,9 @@ public void handle(UpdateNPCsInboundMessage message) {
 
         Npc.parseNpcUpdateMasks(message.appearanceUpdates);
 
-        for(int i = 0; i < MovedStatics.deregisterActorCount; i++) {
+        for (int i = 0; i < MovedStatics.deregisterActorCount; i++) {
             int trackedNpcIndex = Player.deregisterActorIndices[i];
-            if(MovedStatics.pulseCycle != Player.npcs[trackedNpcIndex].anInt3134) {
+            if (Player.npcs[trackedNpcIndex] != null && MovedStatics.pulseCycle != Player.npcs[trackedNpcIndex].anInt3134) {
                 Player.npcs[trackedNpcIndex].actorDefinition = null;
                 Player.npcs[trackedNpcIndex] = null;
             }