diff --git a/build.gradle.kts b/build.gradle.kts
index 571820a..5f611e4 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -14,7 +14,7 @@ plugins {
 }
 
 group = "xland.mcmodbridge"
-version = "3.0.3"
+version = "3.0.4"
 
 repositories {
     maven(url = "https://maven.aliyun.com/repository/public") {
diff --git a/src/main/java/xland/mcmodbridge/fa2fomapper/api/Mapping.java b/src/main/java/xland/mcmodbridge/fa2fomapper/api/Mapping.java
index 448b3f4..05dbaf0 100644
--- a/src/main/java/xland/mcmodbridge/fa2fomapper/api/Mapping.java
+++ b/src/main/java/xland/mcmodbridge/fa2fomapper/api/Mapping.java
@@ -7,10 +7,7 @@
 import org.objectweb.asm.Type;
 
 import javax.annotation.Nonnull;
-import java.util.Arrays;
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
+import java.util.*;
 
 public class Mapping {
     private final BiMap<Type, Type> classes;
@@ -50,6 +47,24 @@ public String getName() {
         public Type getDesc() {
             return desc;
         }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            NodeElement that = (NodeElement) o;
+            return Objects.equals(owner, that.owner) && Objects.equals(name, that.name) && Objects.equals(desc, that.desc);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(owner, name, desc);
+        }
+
+        @Override
+        public String toString() {
+            return owner + "." + name + ':' + desc;
+        }
     }
 
     public static Builder builder() { return new Builder(); }
@@ -196,4 +211,13 @@ public NodeElement mapMethod(NodeElement element) {
     public static Mapping empty() {
         return new Mapping(ImmutableBiMap.of(), Collections.emptyMap(), Collections.emptyMap());
     }
+
+    @Override
+    public String toString() {
+        return "Mapping{" +
+                "classes=" + classes +
+                ", fields=" + fields +
+                ", methods=" + methods +
+                '}';
+    }
 }