diff --git a/gson/src/test/java/com/google/gson/GsonBuilderTest.java b/gson/src/test/java/com/google/gson/GsonBuilderTest.java
index d1fd0d4fc2..9a7adbae77 100644
--- a/gson/src/test/java/com/google/gson/GsonBuilderTest.java
+++ b/gson/src/test/java/com/google/gson/GsonBuilderTest.java
@@ -16,14 +16,14 @@
 
 package com.google.gson;
 
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonWriter;
+import java.io.IOException;
+import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 import java.lang.reflect.Type;
-
 import junit.framework.TestCase;
 
-import com.google.gson.stream.JsonReader;
-import com.google.gson.stream.JsonWriter;
-
 /**
  * Unit tests for {@link GsonBuilder}.
  *
@@ -41,8 +41,99 @@ public class GsonBuilderTest extends TestCase {
 
   public void testCreatingMoreThanOnce() {
     GsonBuilder builder = new GsonBuilder();
-    builder.create();
-    builder.create();
+    Gson gson = builder.create();
+    assertNotNull(gson);
+    assertNotNull(builder.create());
+
+    builder.setFieldNamingStrategy(new FieldNamingStrategy() {
+      @Override public String translateName(Field f) {
+        return "test";
+      }
+    });
+
+    Gson otherGson = builder.create();
+    assertNotNull(otherGson);
+    // Should be different instances because builder has been modified in the meantime
+    assertNotSame(gson, otherGson);
+  }
+
+  /**
+   * Gson instances should not be affected by subsequent modification of GsonBuilder
+   * which created them.
+   */
+  public void testModificationAfterCreate() {
+    GsonBuilder gsonBuilder = new GsonBuilder();
+    Gson gson = gsonBuilder.create();
+
+    // Modifications of `gsonBuilder` should not affect `gson` object
+    gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
+      @Override public CustomClass1 read(JsonReader in) throws IOException {
+        throw new UnsupportedOperationException();
+      }
+
+      @Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
+        out.value("custom-adapter");
+      }
+    });
+    gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
+      @Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
+        return new JsonPrimitive("custom-hierarchy-adapter");
+      }
+    });
+    gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
+      @Override public CustomClass3 createInstance(Type type) {
+        return new CustomClass3("custom-instance");
+      }
+    });
+
+    assertDefaultGson(gson);
+    // New GsonBuilder created from `gson` should not have been affected by changes
+    // to `gsonBuilder` either
+    assertDefaultGson(gson.newBuilder().create());
+
+    // New Gson instance from modified GsonBuilder should be affected by changes
+    assertCustomGson(gsonBuilder.create());
+  }
+
+  private static void assertDefaultGson(Gson gson) {
+    // Should use default reflective adapter
+    String json1 = gson.toJson(new CustomClass1());
+    assertEquals("{}", json1);
+
+    // Should use default reflective adapter
+    String json2 = gson.toJson(new CustomClass2());
+    assertEquals("{}", json2);
+
+    // Should use default instance creator
+    CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
+    assertEquals(CustomClass3.NO_ARG_CONSTRUCTOR_VALUE, customClass3.s);
+  }
+
+  private static void assertCustomGson(Gson gson) {
+    String json1 = gson.toJson(new CustomClass1());
+    assertEquals("\"custom-adapter\"", json1);
+
+    String json2 = gson.toJson(new CustomClass2());
+    assertEquals("\"custom-hierarchy-adapter\"", json2);
+
+    CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
+    assertEquals("custom-instance", customClass3.s);
+  }
+
+  static class CustomClass1 { }
+  static class CustomClass2 { }
+  static class CustomClass3 {
+    static final String NO_ARG_CONSTRUCTOR_VALUE = "default instance";
+
+    final String s;
+
+    public CustomClass3(String s) {
+      this.s = s;
+    }
+
+    public CustomClass3() {
+      this(NO_ARG_CONSTRUCTOR_VALUE);
+    }
   }
 
   public void testExcludeFieldsWithModifiers() {
@@ -52,20 +143,6 @@ public void testExcludeFieldsWithModifiers() {
     assertEquals("{\"d\":\"d\"}", gson.toJson(new HasModifiers()));
   }
 
-  public void testRegisterTypeAdapterForCoreType() {
-    Type[] types = {
-        byte.class,
-        int.class,
-        double.class,
-        Short.class,
-        Long.class,
-        String.class,
-    };
-    for (Type type : types) {
-      new GsonBuilder().registerTypeAdapter(type, NULL_TYPE_ADAPTER);
-    }
-  }
-
   @SuppressWarnings("unused")
   static class HasModifiers {
     private String a = "a";
@@ -85,6 +162,20 @@ static class HasTransients {
     transient String a = "a";
   }
 
+  public void testRegisterTypeAdapterForCoreType() {
+    Type[] types = {
+        byte.class,
+        int.class,
+        double.class,
+        Short.class,
+        Long.class,
+        String.class,
+    };
+    for (Type type : types) {
+      new GsonBuilder().registerTypeAdapter(type, NULL_TYPE_ADAPTER);
+    }
+  }
+
   public void testDisableJdkUnsafe() {
     Gson gson = new GsonBuilder()
         .disableJdkUnsafe()
diff --git a/gson/src/test/java/com/google/gson/GsonTest.java b/gson/src/test/java/com/google/gson/GsonTest.java
index 742f372d40..4274d26a55 100644
--- a/gson/src/test/java/com/google/gson/GsonTest.java
+++ b/gson/src/test/java/com/google/gson/GsonTest.java
@@ -221,4 +221,151 @@ public void testNewJsonReader_Custom() throws IOException {
     assertEquals("test", jsonReader.nextString());
     jsonReader.close();
   }
+
+  /**
+   * Modifying a GsonBuilder obtained from {@link Gson#newBuilder()} of a
+   * {@code new Gson()} should not affect the Gson instance it came from.
+   */
+  public void testDefaultGsonNewBuilderModification() {
+    Gson gson = new Gson();
+    GsonBuilder gsonBuilder = gson.newBuilder();
+
+    // Modifications of `gsonBuilder` should not affect `gson` object
+    gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
+      @Override public CustomClass1 read(JsonReader in) throws IOException {
+        throw new UnsupportedOperationException();
+      }
+
+      @Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
+        out.value("custom-adapter");
+      }
+    });
+    gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
+      @Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
+        return new JsonPrimitive("custom-hierarchy-adapter");
+      }
+    });
+    gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
+      @Override public CustomClass3 createInstance(Type type) {
+        return new CustomClass3("custom-instance");
+      }
+    });
+
+    assertDefaultGson(gson);
+    // New GsonBuilder created from `gson` should not have been affected by changes either
+    assertDefaultGson(gson.newBuilder().create());
+
+    // But new Gson instance from `gsonBuilder` should use custom adapters
+    assertCustomGson(gsonBuilder.create());
+  }
+
+  private static void assertDefaultGson(Gson gson) {
+    // Should use default reflective adapter
+    String json1 = gson.toJson(new CustomClass1());
+    assertEquals("{}", json1);
+
+    // Should use default reflective adapter
+    String json2 = gson.toJson(new CustomClass2());
+    assertEquals("{}", json2);
+
+    // Should use default instance creator
+    CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
+    assertEquals(CustomClass3.NO_ARG_CONSTRUCTOR_VALUE, customClass3.s);
+  }
+
+  /**
+   * Modifying a GsonBuilder obtained from {@link Gson#newBuilder()} of a custom
+   * Gson instance (created using a GsonBuilder) should not affect the Gson instance
+   * it came from.
+   */
+  public void testNewBuilderModification() {
+    Gson gson = new GsonBuilder()
+      .registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
+        @Override public CustomClass1 read(JsonReader in) throws IOException {
+          throw new UnsupportedOperationException();
+        }
+
+        @Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
+          out.value("custom-adapter");
+        }
+      })
+      .registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
+        @Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
+          return new JsonPrimitive("custom-hierarchy-adapter");
+        }
+      })
+      .registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
+        @Override public CustomClass3 createInstance(Type type) {
+          return new CustomClass3("custom-instance");
+        }
+      })
+      .create();
+
+    assertCustomGson(gson);
+
+    // Modify `gson.newBuilder()`
+    GsonBuilder gsonBuilder = gson.newBuilder();
+    gsonBuilder.registerTypeAdapter(CustomClass1.class, new TypeAdapter<CustomClass1>() {
+      @Override public CustomClass1 read(JsonReader in) throws IOException {
+        throw new UnsupportedOperationException();
+      }
+
+      @Override public void write(JsonWriter out, CustomClass1 value) throws IOException {
+        out.value("overwritten custom-adapter");
+      }
+    });
+    gsonBuilder.registerTypeHierarchyAdapter(CustomClass2.class, new JsonSerializer<CustomClass2>() {
+      @Override public JsonElement serialize(CustomClass2 src, Type typeOfSrc, JsonSerializationContext context) {
+        return new JsonPrimitive("overwritten custom-hierarchy-adapter");
+      }
+    });
+    gsonBuilder.registerTypeAdapter(CustomClass3.class, new InstanceCreator<CustomClass3>() {
+      @Override public CustomClass3 createInstance(Type type) {
+        return new CustomClass3("overwritten custom-instance");
+      }
+    });
+
+    // `gson` object should not have been affected by changes to new GsonBuilder
+    assertCustomGson(gson);
+    // New GsonBuilder based on `gson` should not have been affected either
+    assertCustomGson(gson.newBuilder().create());
+
+    // But new Gson instance from `gsonBuilder` should be affected by changes
+    Gson otherGson = gsonBuilder.create();
+    String json1 = otherGson.toJson(new CustomClass1());
+    assertEquals("\"overwritten custom-adapter\"", json1);
+
+    String json2 = otherGson.toJson(new CustomClass2());
+    assertEquals("\"overwritten custom-hierarchy-adapter\"", json2);
+
+    CustomClass3 customClass3 = otherGson.fromJson("{}", CustomClass3.class);
+    assertEquals("overwritten custom-instance", customClass3.s);
+  }
+
+  private static void assertCustomGson(Gson gson) {
+    String json1 = gson.toJson(new CustomClass1());
+    assertEquals("\"custom-adapter\"", json1);
+
+    String json2 = gson.toJson(new CustomClass2());
+    assertEquals("\"custom-hierarchy-adapter\"", json2);
+
+    CustomClass3 customClass3 = gson.fromJson("{}", CustomClass3.class);
+    assertEquals("custom-instance", customClass3.s);
+  }
+
+  static class CustomClass1 { }
+  static class CustomClass2 { }
+  static class CustomClass3 {
+    static final String NO_ARG_CONSTRUCTOR_VALUE = "default instance";
+
+    final String s;
+
+    public CustomClass3(String s) {
+      this.s = s;
+    }
+
+    public CustomClass3() {
+      this(NO_ARG_CONSTRUCTOR_VALUE);
+    }
+  }
 }