diff --git a/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/ECS.java b/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/ECS.java
index 00937ea..b0061e0 100644
--- a/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/ECS.java
+++ b/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/ECS.java
@@ -46,11 +46,15 @@ public class ECS {
     }
 
     /**
+     * /**
      * Creates a new entity
-     * @return the id of the new entity
+     * @return the index of the new entity
+     * @throws IndexOutOfBoundsException
      */
-    Integer createEntity(){
-        return entityManager.addEntity();
+    Integer createEntity() throws IndexOutOfBoundsException{
+        int newEntity = entityManager.addEntity();
+        if (newEntity == -1) throw new IndexOutOfBoundsException("Could not create a new entity");
+        return newEntity;
     }
 
     /**
diff --git a/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/EntityManager.java b/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/EntityManager.java
index bc9edf6..50999b6 100644
--- a/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/EntityManager.java
+++ b/javaecs/src/main/java/nz/ac/massey/programming_project_159333_s1_2021/EntityManager.java
@@ -65,6 +65,10 @@ class EntityManager{
     }
 
     public void registerComponent(int component, int entity){
+        if (entity >= currentSize){
+            System.err.println("Attempted to assign a component to non-existent entity: " + entity);
+            return;
+        }
         entityRegistrations.get(entity).set(component);
     }
 
diff --git a/javaecs/src/test/java/nz/ac/massey/programming_project_159333_s1_2021/AppTest.java b/javaecs/src/test/java/nz/ac/massey/programming_project_159333_s1_2021/AppTest.java
index a883222..e52124e 100644
--- a/javaecs/src/test/java/nz/ac/massey/programming_project_159333_s1_2021/AppTest.java
+++ b/javaecs/src/test/java/nz/ac/massey/programming_project_159333_s1_2021/AppTest.java
@@ -3,7 +3,9 @@ package nz.ac.massey.programming_project_159333_s1_2021;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.util.BitSet;
 
@@ -58,8 +60,15 @@ class AppTest {
     @Test
     void testAssignMoreThanMax(){
         for (int i = 0; i < gameEngine.getMaxEntities() + 5; i++) {
-            int entity = gameEngine.createEntity();
-            gameEngine.addComponent(entity, TestObject.class, new TestObject());
+            if (i >= gameEngine.getMaxEntities()){
+                assertThrows(IndexOutOfBoundsException.class, () -> {
+                    int entity = gameEngine.createEntity();
+                });
+            }
+            else{
+                int entity = gameEngine.createEntity();
+                gameEngine.addComponent(entity, TestObject.class, new TestObject());
+            }
         }
     }
 
@@ -135,6 +144,23 @@ class AppTest {
         gameEngine.resizeMaximum(1024 - 255);
     }
 
+    /**
+     * Test large creations & deletions & smaller resize, to a value too small
+     */
+    @Test
+    void testLargeCreateDeleteResizeTooSmall(){
+        for (int i = 0; i < gameEngine.getMaxEntities(); i++) {
+            int entity = gameEngine.createEntity();
+            gameEngine.addComponent(entity, TestObject.class, new TestObject());
+            assertEquals(1, ((TestObject)gameEngine.getComponentData(entity, TestObject.class)).i);
+        }
+        for (int i = 256; i < 512; i++) {
+            gameEngine.destroyEntity(i);
+        }
+        assertFalse(gameEngine.resizeMaximum(512));
+        
+    }
+
 
     /**
      * Establish a simple ECS, with a single system and component