diff --git a/runelite-api/src/main/java/net/runelite/api/events/NpcCompositionChanged.java b/runelite-api/src/main/java/net/runelite/api/events/NpcCompositionChanged.java
new file mode 100644
index 0000000000..29cdd890b6
--- /dev/null
+++ b/runelite-api/src/main/java/net/runelite/api/events/NpcCompositionChanged.java
@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2018, Woox <https://github.com/wooxsolo>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
+ * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.runelite.api.events;
+
+import lombok.Value;
+import net.runelite.api.NPC;
+
+/**
+ * Fires after the composition of an {@link NPC} changes.
+ */
+@Value
+public class NpcCompositionChanged
+{
+	/**
+	 * The NPC of which the composition changed.
+	 */
+	private final NPC npc;
+}
\ No newline at end of file
diff --git a/runelite-mixins/src/main/java/net/runelite/mixins/RSNPCMixin.java b/runelite-mixins/src/main/java/net/runelite/mixins/RSNPCMixin.java
index ea0f74f93c..9b58f3eb2c 100644
--- a/runelite-mixins/src/main/java/net/runelite/mixins/RSNPCMixin.java
+++ b/runelite-mixins/src/main/java/net/runelite/mixins/RSNPCMixin.java
@@ -24,12 +24,13 @@
  */
 package net.runelite.mixins;
 
+import java.awt.Polygon;
 import net.runelite.api.AnimationID;
 import net.runelite.api.NPCDefinition;
 import net.runelite.api.Perspective;
 import net.runelite.api.coords.LocalPoint;
+import net.runelite.api.events.NpcCompositionChanged;
 import net.runelite.api.events.NpcDespawned;
-import java.awt.Polygon;
 import net.runelite.api.mixins.Copy;
 import net.runelite.api.mixins.FieldHook;
 import net.runelite.api.mixins.Inject;
@@ -113,6 +114,16 @@ public abstract class RSNPCMixin implements RSNPC
 		}
 	}
 
+	@FieldHook("definition")
+	@Inject
+	public void afterCompositionChanged(int idx)
+	{
+		if (this.getDefinition() != null && this.getId() != -1)
+		{
+			client.getCallbacks().post(new NpcCompositionChanged(this));
+		}
+	}
+
 	@Copy("getModel")
 	public abstract RSModel rs$getModel();