diff --git a/src/main/java/it/cavallium/strangedb/database/blocks/DatabaseBlocksMetadata.java b/src/main/java/it/cavallium/strangedb/database/blocks/DatabaseBlocksMetadata.java
index 038190e..7a48e4c 100644
--- a/src/main/java/it/cavallium/strangedb/database/blocks/DatabaseBlocksMetadata.java
+++ b/src/main/java/it/cavallium/strangedb/database/blocks/DatabaseBlocksMetadata.java
@@ -43,6 +43,9 @@ public class DatabaseBlocksMetadata implements IBlocksMetadata {
 		long position = blockId * BLOCK_META_BYTES_COUNT;
 		int size = BLOCK_META_READS_AT_EVERY_READ * BLOCK_META_BYTES_COUNT;
 		long currentFirstFreeBlock = this.firstFreeBlock.get();
+		if (blockId > currentFirstFreeBlock) {
+			return EMPTY_BLOCK_INFO;
+		}
 		if (blockId + (size - 1) / BLOCK_META_BYTES_COUNT >= currentFirstFreeBlock) {
 			size = (int) ((currentFirstFreeBlock - blockId) * BLOCK_META_BYTES_COUNT);
 		}
diff --git a/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesIO.java b/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesIO.java
index ef528d1..1fc0647 100644
--- a/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesIO.java
+++ b/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesIO.java
@@ -33,9 +33,9 @@ public class DatabaseReferencesIO implements IReferencesIO {
 
 	@Override
 	public void writeToReference(long reference, byte cleanerId, int size, ByteBuffer data) throws IOException {
+		long blockId = (size == 0) ? EMPTY_BLOCK_ID : blocksIO.newBlock(size, data);
 		lock.writeLock().lock();
 		try {
-			long blockId = (size == 0) ? EMPTY_BLOCK_ID : blocksIO.newBlock(size, data);
 			referencesMetadata.editReference(reference, cleanerId, blockId);
 		} finally {
 			lock.writeLock().unlock();
diff --git a/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesMetadata.java b/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesMetadata.java
index 5d4a04f..ce3c3ab 100644
--- a/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesMetadata.java
+++ b/src/main/java/it/cavallium/strangedb/database/references/DatabaseReferencesMetadata.java
@@ -58,6 +58,9 @@ public class DatabaseReferencesMetadata implements IReferencesMetadata {
 		}
 		long position = reference * REF_META_BYTES_COUNT;
 		int size = REF_META_READS_AT_EVERY_READ * REF_META_BYTES_COUNT;
+		if (reference > firstFreeReference) {
+			return EMPTY_BLOCK_ID;
+		}
 		if (reference + (size - 1) / REF_META_BYTES_COUNT >= firstFreeReference) {
 			size = (int) ((firstFreeReference - reference) * REF_META_BYTES_COUNT);
 		}