diff --git a/gson/src/main/java/com/google/gson/JsonSerializationVisitor.java b/gson/src/main/java/com/google/gson/JsonSerializationVisitor.java
index e3b499a8..049876dd 100644
--- a/gson/src/main/java/com/google/gson/JsonSerializationVisitor.java
+++ b/gson/src/main/java/com/google/gson/JsonSerializationVisitor.java
@@ -184,7 +184,9 @@ final class JsonSerializationVisitor implements ObjectNavigator.Visitor {
     objTypePair = pair.getSecond();
     start(objTypePair);
     try {
-      return serializer.serialize(objTypePair.getObject(), objTypePair.getType(), context);
+      JsonElement element = 
+        serializer.serialize(objTypePair.getObject(), objTypePair.getType(), context);
+      return element == null ? JsonNull.createJsonNull() : element;
     } finally {
       end(objTypePair);
     }
diff --git a/gson/src/test/java/com/google/gson/functional/CustomSerializerTest.java b/gson/src/test/java/com/google/gson/functional/CustomSerializerTest.java
index e77f416f..ecc06949 100644
--- a/gson/src/test/java/com/google/gson/functional/CustomSerializerTest.java
+++ b/gson/src/test/java/com/google/gson/functional/CustomSerializerTest.java
@@ -16,11 +16,17 @@
 
 package com.google.gson.functional;
 
+import java.lang.reflect.Type;
+
+import junit.framework.TestCase;
+
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonSerializationContext;
+import com.google.gson.JsonSerializer;
 import com.google.gson.common.TestTypes.Base;
 import com.google.gson.common.TestTypes.BaseSerializer;
 import com.google.gson.common.TestTypes.ClassWithBaseArrayField;
@@ -28,8 +34,6 @@ import com.google.gson.common.TestTypes.ClassWithBaseField;
 import com.google.gson.common.TestTypes.Sub;
 import com.google.gson.common.TestTypes.SubSerializer;
 
-import junit.framework.TestCase;
-
 /**
  * Functional Test exercising custom serialization only.  When test applies to both 
  * serialization and deserialization then add it to CustomTypeAdapterTest.
@@ -83,4 +87,17 @@ public class CustomSerializerTest extends TestCase {
      JsonObject base = json.get("base").getAsJsonObject();
      assertEquals(BaseSerializer.NAME, base.get(Base.SERIALIZER_KEY).getAsString());
    }
+   
+   public void testSerializerReturnsNull() {
+     Gson gson = new GsonBuilder()
+       .registerTypeAdapter(Base.class, new JsonSerializer<Base>() {
+         public JsonElement serialize(Base src, Type typeOfSrc, JsonSerializationContext context) {
+           return null;
+         }         
+       })
+       .create();
+       JsonElement json = gson.toJsonTree(new Base());       
+       System.out.println(json);
+       assertTrue(json.isJsonNull());
+   }
 }