diff --git a/src/main/java/de/maltemoeser/bcgraph/blockchain/AbstractBlockChainBuilder.java b/src/main/java/de/maltemoeser/bcgraph/blockchain/AbstractBlockChainBuilder.java
index 8349efe..f47b18e 100644
--- a/src/main/java/de/maltemoeser/bcgraph/blockchain/AbstractBlockChainBuilder.java
+++ b/src/main/java/de/maltemoeser/bcgraph/blockchain/AbstractBlockChainBuilder.java
@@ -64,10 +64,12 @@ protected void constructSetOfValidHashes() throws BlockStoreException {
         Collections.reverse(blockHashesInCorrectOrder);
     }
 
+    @Override
     public SimplifiedBlockChain getSimplifiedValidBlockChain() {
         return new SimplifiedBlockChain(blockHashToHeight, blockHashesInCorrectOrder);
     }
 
+    @Override
     public BlockChain getChain() {
         return chain;
     }
diff --git a/src/main/java/de/maltemoeser/bcgraph/database/ProductionDatabase.java b/src/main/java/de/maltemoeser/bcgraph/database/ProductionDatabase.java
index a23f469..4bf6ef8 100644
--- a/src/main/java/de/maltemoeser/bcgraph/database/ProductionDatabase.java
+++ b/src/main/java/de/maltemoeser/bcgraph/database/ProductionDatabase.java
@@ -23,6 +23,7 @@ public ProductionDatabase(ApplicationConfig properties) {
         waitUntilIndexesAreOnline();
     }
 
+    @Override
     public void initialize() {
         initializeInDirectory(properties.getDatabaseDirectory());
     }
diff --git a/src/main/java/de/maltemoeser/bcgraph/database/ReadOnlyDatabase.java b/src/main/java/de/maltemoeser/bcgraph/database/ReadOnlyDatabase.java
index 62a5ba5..f2d816d 100644
--- a/src/main/java/de/maltemoeser/bcgraph/database/ReadOnlyDatabase.java
+++ b/src/main/java/de/maltemoeser/bcgraph/database/ReadOnlyDatabase.java
@@ -23,6 +23,7 @@ public ReadOnlyDatabase(ApplicationConfig properties) {
         waitUntilIndexesAreOnline();
     }
 
+    @Override
     public void initialize() {
         initializeInDirectory(properties.getDatabaseDirectory());
     }