diff --git a/numass-core/src/main/kotlin/inr/numass/data/api/NumassSet.kt b/numass-core/src/main/kotlin/inr/numass/data/api/NumassSet.kt
index 741a6c3b..c5c6c0f2 100644
--- a/numass-core/src/main/kotlin/inr/numass/data/api/NumassSet.kt
+++ b/numass-core/src/main/kotlin/inr/numass/data/api/NumassSet.kt
@@ -72,6 +72,7 @@ interface NumassSet : Named, Metoid, Iterable<NumassPoint>, Provider {
         return optPoint(java.lang.Double.parseDouble(voltage))
     }
 
+    @JvmDefault
     override fun getDefaultTarget(): String {
         return NUMASS_POINT_PROVIDER_KEY
     }
diff --git a/numass-main/src/main/java/inr/numass/models/GunTailSpectrum.java b/numass-main/src/main/java/inr/numass/models/GunTailSpectrum.java
index 886bc191..8895a13d 100644
--- a/numass-main/src/main/java/inr/numass/models/GunTailSpectrum.java
+++ b/numass-main/src/main/java/inr/numass/models/GunTailSpectrum.java
@@ -16,6 +16,7 @@
 package inr.numass.models;
 
 import hep.dataforge.exceptions.NotDefinedException;
+import hep.dataforge.names.NameList;
 import hep.dataforge.values.ValueProvider;
 import hep.dataforge.values.Values;
 import org.apache.commons.math3.analysis.UnivariateFunction;
@@ -44,8 +45,8 @@ public class GunTailSpectrum implements RangedNamedSetSpectrum {
     }
 
     @Override
-    public Names getNames() {
-        return Names.of(list);
+    public NameList getNames() {
+        return new NameList(list);
     }
 
     @Override