diff --git a/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionary.java b/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionary.java
index 4284cb9..a2bffe8 100644
--- a/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionary.java
+++ b/src/main/java/it/cavallium/dbengine/database/collections/DatabaseMapDictionary.java
@@ -11,7 +11,6 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
-import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.Function;
 import org.jetbrains.annotations.Nullable;
 import reactor.core.publisher.Flux;
@@ -111,7 +110,6 @@ public class DatabaseMapDictionary<T, U> extends DatabaseMapDictionaryDeep<T, U,
 
 	@Override
 	public Mono<Boolean> updateValue(T keySuffix, Function<Optional<U>, Optional<U>> updater) {
-		AtomicBoolean changed = new AtomicBoolean(false);
 		return dictionary.update(toKey(serializeSuffix(keySuffix)),
 				oldSerialized -> updater.apply(oldSerialized.map(this::deserialize)).map(this::serialize)
 		);
diff --git a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
index 3d61c86..af1e1a5 100644
--- a/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
+++ b/src/main/java/it/cavallium/dbengine/database/disk/LLLocalDictionary.java
@@ -95,7 +95,7 @@ public class LLLocalDictionary implements LLDictionary {
 	}
 
 	private int getLockIndex(byte[] key) {
-		return Arrays.hashCode(key) % STRIPES;
+		return Math.abs(Arrays.hashCode(key) % STRIPES);
 	}
 
 	private IntArrayList getLockIndices(List<byte[]> keys) {
diff --git a/src/main/java/it/cavallium/dbengine/database/serialization/CodecSerializer.java b/src/main/java/it/cavallium/dbengine/database/serialization/CodecSerializer.java
index 71dcf77..7305187 100644
--- a/src/main/java/it/cavallium/dbengine/database/serialization/CodecSerializer.java
+++ b/src/main/java/it/cavallium/dbengine/database/serialization/CodecSerializer.java
@@ -4,6 +4,7 @@ import io.netty.buffer.ByteBuf;
 import io.netty.buffer.ByteBufInputStream;
 import io.netty.buffer.ByteBufOutputStream;
 import io.netty.buffer.Unpooled;
+import java.io.IOError;
 import java.io.IOException;
 import org.jetbrains.annotations.NotNull;
 import org.warp.commonutils.error.IndexOutOfBoundsException;
@@ -46,7 +47,7 @@ public class CodecSerializer<A> implements Serializer<A, byte[]> {
 			return serializer.deserialize(is);
 		} catch (IOException ex) {
 			// This shouldn't happen
-			throw new RuntimeException(ex);
+			throw new IOError(ex);
 		}
 	}
 
@@ -66,7 +67,15 @@ public class CodecSerializer<A> implements Serializer<A, byte[]> {
 			return bytes;
 		} catch (IOException ex) {
 			// This shouldn't happen
-			throw new RuntimeException(ex);
+			throw new IOError(ex);
+		}
+	}
+
+	public int getCodecHeadersBytes() {
+		if (microCodecs) {
+			return Byte.BYTES;
+		} else {
+			return Integer.BYTES;
 		}
 	}
 }