diff --git a/msgpack-core/src/main/java/org/msgpack/value/ValueType.java b/msgpack-core/src/main/java/org/msgpack/value/ValueType.java
index 715ebbd18..91b2a585f 100644
--- a/msgpack-core/src/main/java/org/msgpack/value/ValueType.java
+++ b/msgpack-core/src/main/java/org/msgpack/value/ValueType.java
@@ -28,7 +28,7 @@ public enum ValueType
     BINARY(false, true),
     ARRAY(false, false),
     MAP(false, false),
-    EXTENSION(false, true);
+    EXTENSION(false, false);
 
     private final boolean numberType;
     private final boolean rawType;
diff --git a/msgpack-core/src/test/scala/org/msgpack/value/ValueFactoryTest.scala b/msgpack-core/src/test/scala/org/msgpack/value/ValueFactoryTest.scala
index a8d996376..6b045f3ae 100644
--- a/msgpack-core/src/test/scala/org/msgpack/value/ValueFactoryTest.scala
+++ b/msgpack-core/src/test/scala/org/msgpack/value/ValueFactoryTest.scala
@@ -62,7 +62,7 @@ class ValueFactoryTest
       isValid(ValueFactory.emptyArray(), expected = ValueType.ARRAY, isArray = true)
       isValid(ValueFactory.emptyMap(), expected = ValueType.MAP, isMap = true)
       forAll { (v: Array[Byte]) => isValid(ValueFactory.newExtension(0, v), expected = ValueType
-        .EXTENSION, isExtension = true, isRaw = true)
+        .EXTENSION, isExtension = true, isRaw = false)
       }
     }
   }