diff --git a/src/main/java/me/mrletsplay/shareclientcore/document/SharedDocument.java b/src/main/java/me/mrletsplay/shareclientcore/document/SharedDocument.java
index 048576f..8aa6b33 100644
--- a/src/main/java/me/mrletsplay/shareclientcore/document/SharedDocument.java
+++ b/src/main/java/me/mrletsplay/shareclientcore/document/SharedDocument.java
@@ -56,7 +56,7 @@ public class SharedDocument implements MessageListener {
 			Identifier[] newPos = Util.generatePositionBetween(charBefore.position(), charAfter.position(), site);
 			lamport++;
 			Char ch = new Char(newPos, lamport, bytes[i]);
-			charBag.add(ch);
+			if(charBag.add(ch) == -1) throw new IllegalStateException("Couldn't insert newly created char");
 			changes[i] = new Change(path, ChangeType.ADD, ch);
 			charBefore = ch;
 		}
@@ -110,7 +110,7 @@ public class SharedDocument implements MessageListener {
 			// TODO: more efficient implementation (e.g. range delete in CharBag)
 			Char toRemove = charBag.get(index + 1);
 			changes[n] = new Change(path, ChangeType.REMOVE, toRemove);
-			charBag.remove(toRemove);
+			if(charBag.remove(toRemove) == -1) throw new IllegalStateException("Couldn't remove existing char");
 		}
 
 
@@ -195,7 +195,6 @@ public class SharedDocument implements MessageListener {
 			Change c = change.change();
 			if(!c.documentPath().equals(path)) return;
 
-			System.out.println("Change: " + c + " | " + Arrays.toString(c.character().position()));
 			switch(c.type()) {
 				case ADD -> remoteInsert(c.character());
 				case REMOVE -> remoteDelete(c.character());
diff --git a/src/main/java/me/mrletsplay/shareclientcore/document/Util.java b/src/main/java/me/mrletsplay/shareclientcore/document/Util.java
index 462c89a..3257f31 100644
--- a/src/main/java/me/mrletsplay/shareclientcore/document/Util.java
+++ b/src/main/java/me/mrletsplay/shareclientcore/document/Util.java
@@ -1,6 +1,7 @@
 package me.mrletsplay.shareclientcore.document;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 
 public class Util {
@@ -44,6 +45,10 @@ public class Util {
 				return newPosition.toArray(Identifier[]::new);
 			}
 
+			System.err.println("Got invalid state");
+			System.err.println(c1 + "/" + c2);
+			System.err.println(Arrays.toString(before));
+			System.err.println(Arrays.toString(after));
 			throw new RuntimeException("Invalid site order");
 		}
 
diff --git a/src/test/java/me/mrletsplay/shareclientcore/SharingTest.java b/src/test/java/me/mrletsplay/shareclientcore/SharingTest.java
index a2cd7e8..e5cb6ee 100644
--- a/src/test/java/me/mrletsplay/shareclientcore/SharingTest.java
+++ b/src/test/java/me/mrletsplay/shareclientcore/SharingTest.java
@@ -2,6 +2,8 @@ package me.mrletsplay.shareclientcore;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
+import java.util.Random;
+
 import org.junit.jupiter.api.Test;
 
 import me.mrletsplay.shareclientcore.connection.DummyConnection;
@@ -32,6 +34,69 @@ public class SharingTest {
 
 		assertEquals("This is a test!Hello World!", sharedA.getContentsAsString());
 		assertEquals("This is a test!Hello World!", sharedB.getContentsAsString());
+
+		sharedA.localDelete(10, 11);
+
+		assertEquals("This is a World!", sharedA.getContentsAsString());
+		assertEquals("This is a World!", sharedB.getContentsAsString());
+
+		sharedB.localDelete(7, 8);
+
+		assertEquals("This is!", sharedA.getContentsAsString());
+		assertEquals("This is!", sharedB.getContentsAsString());
+	}
+
+	@Test
+	public void testSharedDocument2() {
+		DummyConnection a = new DummyConnection(0);
+		DummyConnection b = new DummyConnection(1);
+
+		a.setSendMessageHandler(m -> b.receive(m));
+		b.setSendMessageHandler(m -> a.receive(m));
+
+		SharedDocument sharedA = new SharedDocument(a, "doc");
+		SharedDocument sharedB = new SharedDocument(b, "doc");
+
+		a.addListener(sharedA);
+		b.addListener(sharedB);
+
+		String chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890";
+
+		Random r = new Random(0);
+		for(int i = 0; i < 1000; i++) {
+			switch(r.nextInt(sharedA.getContents().length == 0 ? 2 : 4)) {
+				case 0: {
+					// Insert A
+					char[] insert = new char[r.nextInt(16)];
+					for(int j = 0; j < insert.length; j++) insert[j] = chars.charAt(r.nextInt(chars.length()));
+					sharedA.localInsert(r.nextInt(sharedA.getContents().length + 1), String.valueOf(insert));
+				}
+				case 1: {
+					// Insert B
+					char[] insert = new char[r.nextInt(16)];
+					for(int j = 0; j < insert.length; j++) insert[j] = chars.charAt(r.nextInt(chars.length()));
+					sharedB.localInsert(r.nextInt(sharedB.getContents().length + 1), String.valueOf(insert));
+				}
+				case 2: {
+					// Delete A
+					int len = sharedA.getContents().length;
+					int idx = r.nextInt(len);
+					int n = r.nextInt(len - idx);
+					sharedA.localDelete(idx, n);
+				}
+				case 3: {
+					// Delete B
+					int len = sharedB.getContents().length;
+					int idx = r.nextInt(len);
+					int n = r.nextInt(len - idx + 1);
+					sharedB.localDelete(idx, n);
+				}
+			}
+
+			System.out.println("A: " + sharedA.getContentsAsString());
+			System.out.println("B: " + sharedB.getContentsAsString());
+			assertEquals(sharedA.getContentsAsString(), sharedB.getContentsAsString());
+		}
 	}
 
 }