diff --git a/java/core/src/main/java/com/google/protobuf/ByteString.java b/java/core/src/main/java/com/google/protobuf/ByteString.java
index 0e03ebd14ee5..1acbad08b4a3 100644
--- a/java/core/src/main/java/com/google/protobuf/ByteString.java
+++ b/java/core/src/main/java/com/google/protobuf/ByteString.java
@@ -75,6 +75,7 @@
  */
 @CheckReturnValue
 public abstract class ByteString implements Iterable<Byte>, Serializable {
+  private static final long serialVersionUID = 1L;
 
   /**
    * When two strings to be concatenated have a combined length shorter than this, we just copy
@@ -945,6 +946,8 @@ public final String toStringUtf8() {
 
   /** Base class for leaf {@link ByteString}s (i.e. non-ropes). */
   abstract static class LeafByteString extends ByteString {
+    private static final long serialVersionUID = 1L;
+
     @Override
     protected final int getTreeDepth() {
       return 0;
@@ -1603,7 +1606,6 @@ protected int getOffsetIntoBytes() {
   // Keep this class private to avoid deadlocks in classloading across threads as ByteString's
   // static initializer loads LiteralByteString and another thread loads BoundedByteString.
   private static final class BoundedByteString extends LiteralByteString {
-
     private final int bytesOffset;
     private final int bytesLength;