diff --git a/src/main/java/com/metaweb/gridworks/history/HistoryEntry.java b/src/main/java/com/metaweb/gridworks/history/HistoryEntry.java
index 1add70827..9afcbc902 100644
--- a/src/main/java/com/metaweb/gridworks/history/HistoryEntry.java
+++ b/src/main/java/com/metaweb/gridworks/history/HistoryEntry.java
@@ -6,7 +6,6 @@ import java.io.FileOutputStream;
 import java.io.InputStreamReader;
 import java.io.LineNumberReader;
 import java.io.OutputStreamWriter;
-import java.io.Serializable;
 import java.io.Writer;
 import java.util.Date;
 import java.util.Properties;
@@ -25,9 +24,7 @@ import com.metaweb.gridworks.model.Project;
 import com.metaweb.gridworks.operations.OperationRegistry;
 import com.metaweb.gridworks.util.ParsingUtilities;
 
-public class HistoryEntry implements Serializable, Jsonizable {
-    private static final long serialVersionUID = 532766467813930262L;
-    
+public class HistoryEntry implements Jsonizable {
     final public long                id;
     final public long                projectID;
     final public String              description;
diff --git a/src/main/java/com/metaweb/gridworks/model/ColumnGroup.java b/src/main/java/com/metaweb/gridworks/model/ColumnGroup.java
index f8ca5f02c..88673c234 100644
--- a/src/main/java/com/metaweb/gridworks/model/ColumnGroup.java
+++ b/src/main/java/com/metaweb/gridworks/model/ColumnGroup.java
@@ -1,7 +1,5 @@
 package com.metaweb.gridworks.model;
 
-import java.io.IOException;
-import java.io.ObjectInputStream;
 import java.io.Writer;
 import java.util.LinkedList;
 import java.util.List;
@@ -74,11 +72,6 @@ public class ColumnGroup implements Jsonizable {
         );
     }
     
-    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
-        in.defaultReadObject();
-        internalInitialize();
-    }
-    
     protected void internalInitialize() {
         subgroups = new LinkedList<ColumnGroup>();
     }
diff --git a/src/main/java/com/metaweb/gridworks/model/changes/CellAtRow.java b/src/main/java/com/metaweb/gridworks/model/changes/CellAtRow.java
index fd935845a..f0e65666c 100644
--- a/src/main/java/com/metaweb/gridworks/model/changes/CellAtRow.java
+++ b/src/main/java/com/metaweb/gridworks/model/changes/CellAtRow.java
@@ -1,14 +1,12 @@
 package com.metaweb.gridworks.model.changes;
 
 import java.io.IOException;
-import java.io.Serializable;
 import java.io.Writer;
 import java.util.Properties;
 
 import com.metaweb.gridworks.model.Cell;
 
 public class CellAtRow {
-    private static final long serialVersionUID = 7280920621006690944L;
 
     final public int    row;
     final public Cell   cell;