diff --git a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
index 2822f25..891de41 100644
--- a/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
+++ b/core/store/dist/src/main/java/org/onlab/onos/store/service/impl/DatabaseStateMachine.java
@@ -5,8 +5,6 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
-import java.util.Set;
-
 import net.kuujo.copycat.Command;
 import net.kuujo.copycat.Query;
 import net.kuujo.copycat.StateMachine;
@@ -20,6 +18,7 @@
 import org.onlab.util.KryoNamespace;
 import org.slf4j.Logger;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.Maps;
 
 /**
@@ -64,8 +63,8 @@
     }
 
     @Query
-    public Set<String> listTables() {
-        return state.getTables().keySet();
+    public List<String> listTables() {
+        return ImmutableList.copyOf(state.getTables().keySet());
     }
 
     @Query