diff --git a/src/java.base/share/classes/java/io/ObjectInputStream.java b/src/java.base/share/classes/java/io/ObjectInputStream.java
index a77a5d5b6..f2791a4cb 100644
--- a/src/java.base/share/classes/java/io/ObjectInputStream.java
+++ b/src/java.base/share/classes/java/io/ObjectInputStream.java
@@ -391,6 +391,11 @@ public class ObjectInputStream
             new sun.security.action.GetBooleanAction(
                     "printFastSerializer")).booleanValue();
 
+    /**
+     * Magic number that is written to the stream header when using fastserilizer.
+     */
+    private static final short STREAM_MAGIC_FAST = (short)0xdeca;
+
     /**
      * Creates an ObjectInputStream that reads from the specified InputStream.
      * A serialization stream header is read from the stream and verified.
@@ -763,7 +768,7 @@ public class ObjectInputStream
      * Cache the class meta during serialization.
      * Only used in FastSerilizer.
      */
-    protected static ConcurrentHashMap<String,Class<?>> nameToClass = new ConcurrentHashMap<>();
+    private static ConcurrentHashMap<String,Class<?>> nameToClass = new ConcurrentHashMap<>();
 
     /**
      * Load the local class equivalent of the specified stream class
diff --git a/src/java.base/share/classes/java/io/ObjectOutputStream.java b/src/java.base/share/classes/java/io/ObjectOutputStream.java
index 8935e61dc..0e5476395 100644
--- a/src/java.base/share/classes/java/io/ObjectOutputStream.java
+++ b/src/java.base/share/classes/java/io/ObjectOutputStream.java
@@ -250,6 +250,11 @@ public class ObjectOutputStream
             new sun.security.action.GetBooleanAction(
                     "printFastSerializer")).booleanValue();
 
+    /**
+     * Magic number that is written to the stream header when using fastserilizer.
+     */
+    private static final short STREAM_MAGIC_FAST = (short)0xdeca;
+
     /**
      * Creates an ObjectOutputStream that writes to the specified OutputStream.
      * This constructor writes the serialization stream header to the
diff --git a/src/java.base/share/classes/java/io/ObjectStreamClass.java b/src/java.base/share/classes/java/io/ObjectStreamClass.java
index a5d7d2d75..e37a7841e 100644
--- a/src/java.base/share/classes/java/io/ObjectStreamClass.java
+++ b/src/java.base/share/classes/java/io/ObjectStreamClass.java
@@ -280,7 +280,7 @@ public class ObjectStreamClass implements Serializable {
      *
      * @return the flags for this class described by this descriptor
      */
-    public byte getFlags(Object serialStream) {
+    byte getFlags(Object serialStream) {
         byte flags = 0;
         if (externalizable) {
             flags |= ObjectStreamConstants.SC_EXTERNALIZABLE;
diff --git a/src/java.base/share/classes/java/io/ObjectStreamConstants.java b/src/java.base/share/classes/java/io/ObjectStreamConstants.java
index 96157782a..43a480ce4 100644
--- a/src/java.base/share/classes/java/io/ObjectStreamConstants.java
+++ b/src/java.base/share/classes/java/io/ObjectStreamConstants.java
@@ -38,11 +38,6 @@ public interface ObjectStreamConstants {
      */
     static final short STREAM_MAGIC = (short)0xaced;
 
-    /**
-     * Magic number that is written to the stream header when using fastserilizer.
-     */
-    static final short STREAM_MAGIC_FAST = (short)0xdeca;
-
     /**
      * Version number that is written to the stream header.
      */
-- 
2.19.0