1 files changed, 7 insertions, 0 deletions
diff --git a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
index 46cd86f..8244164 100644
--- a/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
+++ b/java/src/main/java/com/google/protobuf/nano/ExtendableMessageNano.java
@@ -184,4 +184,11 @@ public abstract class ExtendableMessageNano<M extends ExtendableMessageNano<M>>
         return (unknownFieldData == null || unknownFieldData.isEmpty()
                 ? 0 : unknownFieldData.hashCode());
     }
+
+    @Override
+    public M clone() throws CloneNotSupportedException {
+        M cloned = (M) super.clone();
+        InternalNano.cloneUnknownFieldData(this, cloned);
+        return cloned;
+    }
 }