diff --git a/jme3-networking/src/test/java/com/jme3/network/message/Vector3SerializerTest.java b/jme3-networking/src/test/java/com/jme3/network/message/Vector3SerializerTest.java
new file mode 100644
index 0000000000..f05b0ab7c3
--- /dev/null
+++ b/jme3-networking/src/test/java/com/jme3/network/message/Vector3SerializerTest.java
@@ -0,0 +1,102 @@
+/*
+ * Copyright (c) 2026 jMonkeyEngine
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ * * Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * * Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * * Neither the name of 'jMonkeyEngine' nor the names of its contributors
+ *   may be used to endorse or promote products derived from this software
+ *   without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.jme3.network.serializing.serializers;
+
+import com.jme3.math.Vector3f;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotSame;
+
+/**
+ * Round-trip tests for {@link Vector3Serializer}, which encodes positions and
+ * directions in multiplayer messages.
+ */
+public class Vector3SerializerTest {
+
+    private static final int BYTES_PER_VECTOR = 12;
+
+    @Test
+    public void testRoundTripPreservesComponents() throws IOException {
+        Vector3Serializer serializer = new Vector3Serializer();
+        Vector3f original = new Vector3f(1.25f, -2.5f, 3.75f);
+
+        ByteBuffer buffer = ByteBuffer.allocate(BYTES_PER_VECTOR);
+        serializer.writeObject(buffer, original);
+        buffer.flip();
+
+        Vector3f decoded = serializer.readObject(buffer, Vector3f.class);
+
+        assertNotSame(original, decoded);
+        assertEquals(original.x, decoded.x, 0f);
+        assertEquals(original.y, decoded.y, 0f);
+        assertEquals(original.z, decoded.z, 0f);
+        assertEquals(BYTES_PER_VECTOR, buffer.position());
+    }
+
+    @Test
+    public void testRoundTripZeroVector() throws IOException {
+        Vector3Serializer serializer = new Vector3Serializer();
+        Vector3f original = new Vector3f(0, 0, 0);
+
+        ByteBuffer buffer = ByteBuffer.allocate(BYTES_PER_VECTOR);
+        serializer.writeObject(buffer, original);
+        buffer.flip();
+
+        Vector3f decoded = serializer.readObject(buffer, Vector3f.class);
+
+        assertEquals(0f, decoded.x, 0f);
+        assertEquals(0f, decoded.y, 0f);
+        assertEquals(0f, decoded.z, 0f);
+    }
+
+    @Test
+    public void testSequentialVectorsDoNotShareState() throws IOException {
+        Vector3Serializer serializer = new Vector3Serializer();
+        Vector3f first = new Vector3f(1, 2, 3);
+        Vector3f second = new Vector3f(4, 5, 6);
+
+        ByteBuffer buffer = ByteBuffer.allocate(BYTES_PER_VECTOR * 2);
+        serializer.writeObject(buffer, first);
+        serializer.writeObject(buffer, second);
+        buffer.flip();
+
+        Vector3f decodedFirst = serializer.readObject(buffer, Vector3f.class);
+        Vector3f decodedSecond = serializer.readObject(buffer, Vector3f.class);
+
+        assertEquals(1f, decodedFirst.x, 0f);
+        assertEquals(4f, decodedSecond.x, 0f);
+        assertEquals(BYTES_PER_VECTOR * 2, buffer.position());
+    }
+}