diff --git a/core/src/main/java/hudson/model/Items.java b/core/src/main/java/hudson/model/Items.java
index 9b0993dfb2c4da99012dd2c745a6048dc610b403..91e03b809f3568f86f1dbb65a423f5917875970d 100644
--- a/core/src/main/java/hudson/model/Items.java
+++ b/core/src/main/java/hudson/model/Items.java
@@ -26,10 +26,7 @@ package hudson.model;
 import com.thoughtworks.xstream.XStream;
 import hudson.DescriptorExtensionList;
 import hudson.Extension;
-import hudson.matrix.MatrixProject;
-import hudson.matrix.MatrixConfiguration;
 import hudson.XmlFile;
-import hudson.matrix.Axis;
 import hudson.model.listeners.ItemListener;
 import hudson.remoting.Callable;
 import hudson.triggers.Trigger;
@@ -404,8 +401,5 @@ public class Items {
 
     static {
         XSTREAM.alias("project",FreeStyleProject.class);
-        XSTREAM.alias("matrix-project",MatrixProject.class);
-        XSTREAM.alias("axis", Axis.class);
-        XSTREAM.alias("matrix-config",MatrixConfiguration.class);
     }
 }
diff --git a/core/src/main/java/hudson/model/Run.java b/core/src/main/java/hudson/model/Run.java
index b8540ebfea36088e5d97c47d5deddd749b0d29d6..8708fbdf252cc290c264f63c5e3b36436592908d 100644
--- a/core/src/main/java/hudson/model/Run.java
+++ b/core/src/main/java/hudson/model/Run.java
@@ -39,8 +39,6 @@ import hudson.XmlFile;
 import hudson.cli.declarative.CLIMethod;
 import hudson.console.AnnotatedLargeText;
 import hudson.console.ConsoleNote;
-import hudson.matrix.MatrixBuild;
-import hudson.matrix.MatrixRun;
 import hudson.model.Descriptor.FormException;
 import hudson.model.listeners.RunListener;
 import hudson.model.listeners.SaveableListener;
@@ -2263,8 +2261,6 @@ public abstract class Run <JobT extends Job<JobT,RunT>,RunT extends Run<JobT,Run
 
     static {
         XSTREAM.alias("build",FreeStyleBuild.class);
-        XSTREAM.alias("matrix-build",MatrixBuild.class);
-        XSTREAM.alias("matrix-run",MatrixRun.class);
         XSTREAM.registerConverter(Result.conv);
     }