diff --git a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
index b0c3fd1..8dfa82f 100644
--- a/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
+++ b/data-store/src/main/java/org/lucares/pdb/datastore/internal/DataStore.java
@@ -70,6 +70,7 @@ public class DataStore {
 
 		});
 		trimIntLists();
+		((ArrayList<Doc>)docIdToDoc).trimToSize();
 	}
 
 	private void cacheTagToFileMapping(final Tags tags, final Path path) {