diff --git a/src/main/java/org/apache/commons/math3/ml/neuralnet/oned/NeuronString.java b/src/main/java/org/apache/commons/math3/ml/neuralnet/oned/NeuronString.java
index f904c523d..0d8013271 100644
--- a/src/main/java/org/apache/commons/math3/ml/neuralnet/oned/NeuronString.java
+++ b/src/main/java/org/apache/commons/math3/ml/neuralnet/oned/NeuronString.java
@@ -31,6 +31,10 @@ import org.apache.commons.math3.exception.OutOfRangeException;
  * @version $Id$
  */
 public class NeuronString implements Serializable {
+
+    /** Serializable UID. */
+    private static final long serialVersionUID = 20140208L;
+
     /** Underlying network. */
     private final Network network;
     /** Number of neurons. */
diff --git a/src/main/java/org/apache/commons/math3/ml/neuralnet/twod/NeuronSquareMesh2D.java b/src/main/java/org/apache/commons/math3/ml/neuralnet/twod/NeuronSquareMesh2D.java
index c86356bad..65b250217 100644
--- a/src/main/java/org/apache/commons/math3/ml/neuralnet/twod/NeuronSquareMesh2D.java
+++ b/src/main/java/org/apache/commons/math3/ml/neuralnet/twod/NeuronSquareMesh2D.java
@@ -41,6 +41,10 @@ import org.apache.commons.math3.exception.MathInternalError;
  * @version $Id$
  */
 public class NeuronSquareMesh2D implements Serializable {
+
+    /** Serializable UID. */
+    private static final long serialVersionUID = 20140208L;
+
     /** Underlying network. */
     private final Network network;
     /** Number of rows. */