diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
index dcbd6a5dcff..964b0978c5f 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
@@ -11,6 +11,7 @@ public interface ICDescriptor {
 	public String getPlatform();
 	public IProject getProject();
 	public ICExtensionReference[] get(String name);
+	public ICExtensionReference[] get(String name, boolean update);
 	public ICExtensionReference create(String name, String id);
 	public void remove(ICExtensionReference extension);
 }
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICOwner.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICOwner.java
index eeb56d49717..33ee00dd437 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICOwner.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICOwner.java
@@ -6,5 +6,5 @@ package org.eclipse.cdt.core;
 
 public interface ICOwner {
 	public void configure(ICDescriptor cproject);
-	public void update(ICDescriptor cproject);
+	public void update(ICDescriptor cproject, String extensionID);
 }
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptor.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptor.java
index b756f08d701..41c35343066 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptor.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptor.java
@@ -45,7 +45,7 @@ import org.xml.sax.SAXException;
 public class CDescriptor implements ICDescriptor {
 	/* constants */
 	private static final String[] EMPTY_STRING_ARRAY = new String[0];
-	private ICOwnerInfo fOwner;
+	private COwner fOwner;
 	private IProject fProject;
 	private String fPlatform = "*";
 	private HashMap extMap = new HashMap(4);
@@ -57,6 +57,8 @@ public class CDescriptor implements ICDescriptor {
 	private final String PROJECT_EXTENSION = "extension";
 	private final String PROJECT_EXTENSION_ATTRIBUTE = "attribute";
 
+	private boolean fDirty;
+
 	protected void readCDTProject(IPath projectLocation) {
 		FileInputStream file = null;
 		try {
@@ -141,10 +143,24 @@ public class CDescriptor implements ICDescriptor {
 		return fProject;
 	}
 
-	public ICExtensionReference[] get(String name) {
-		return (CExtensionReference[]) extMap.get(name);
+	public ICExtensionReference[] get(String extensionID) {
+		return (CExtensionReference[]) extMap.get(extensionID);
 	}
 	
+	public ICExtensionReference[] get(String extensionID, boolean update) {
+		ICExtensionReference[] ext = get(extensionID);
+		if ( (ext == null || ext.length == 0) && update) {
+			try {
+				fOwner.update(fProject, this, extensionID);
+				saveInfo();
+				ext = get(extensionID);
+			}
+			catch (CoreException e) {
+			}
+		}
+		return ext;
+	}
+
 	public ICExtensionReference create(String name, String id) {
 		CExtensionReference extensions[] = (CExtensionReference[]) extMap.get(name);
 		if ( extensions == null ) {
@@ -156,6 +172,7 @@ public class CDescriptor implements ICDescriptor {
 			extensions = newExtensions;
 			extMap.put(name, extensions);
 		}
+		setDirty();
 		extensions[extensions.length-1] = new CExtensionReference(this, name, id);
 		return extensions[extensions.length-1];
 	}
@@ -173,6 +190,7 @@ public class CDescriptor implements ICDescriptor {
 				} else {
 					extMap.put(ext.getExtension(), extensions);
 				}
+				setDirty();
 			}
 		}
 	}
@@ -200,8 +218,8 @@ public class CDescriptor implements ICDescriptor {
 		return node != null ? (node.getFirstChild() == null ? null : node.getFirstChild().getNodeValue()) : null;
 	}
 
-	private ICOwnerInfo readProjectDescription(Node node) {
-		ICOwnerInfo owner = null;
+	private COwner readProjectDescription(Node node) {
+		COwner owner = null;
 		NamedNodeMap attrib = node.getAttributes();
 		try {
 			owner = new COwner(attrib.getNamedItem("id").getNodeValue());
@@ -254,10 +272,15 @@ public class CDescriptor implements ICDescriptor {
 		} else {
 			rscFile.create(inputStream, IResource.FORCE, null);
 		}
+		fDirty = false;
 	}
 
-	private boolean isDirty() {
-		return true;
+	protected void setDirty() {
+		fDirty = true;
+	}
+	
+	protected boolean isDirty() {
+		return fDirty;
 	}
 
 	protected String serializeDocument(Document doc) throws IOException {
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptorManager.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptorManager.java
index db84fb99d2c..05b1b5819db 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptorManager.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CDescriptorManager.java
@@ -107,7 +107,7 @@ public class CDescriptorManager implements IResourceChangeListener {
 	public ICExtension[] createExtensions(String extensionID, IProject project) throws CoreException {
 		ArrayList extensionList = new ArrayList(1);
 		ICDescriptor cDescriptor = getDescriptor(project);
-		ICExtensionReference ext[] = cDescriptor.get(extensionID);
+		ICExtensionReference ext[] = cDescriptor.get(extensionID, true);
 		IPluginRegistry pluginRegistry = Platform.getPluginRegistry();
 		for( int i = 0; i < ext.length; i++ ) {
 			IExtensionPoint extensionPoint = pluginRegistry.getExtensionPoint(ext[i].getExtension());
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/COwner.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/COwner.java
index 8e3c9045fe3..27700db8c41 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/COwner.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/COwner.java
@@ -89,12 +89,12 @@ public class COwner implements ICOwnerInfo {
 		throw new CoreException(status);
 	}
 
-	void update(IProject project, ICDescriptor cproject) throws CoreException {
+	void update(IProject project, ICDescriptor cproject, String extensionID) throws CoreException {
 		IConfigurationElement element[] = extension.getConfigurationElements();
 		for( int i = 0; i < element.length; i++ ) {
 			if ( element[i].getName().equalsIgnoreCase("run") ) {
 				ICOwner owner = (ICOwner) element[i].createExecutableExtension("class");
-				owner.update(cproject);
+				owner.update(cproject, extensionID);
 				return;
 			}
 		}
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/make/MakeProject.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/make/MakeProject.java
index dda857f06d3..fca9ebb0c18 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/make/MakeProject.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/make/MakeProject.java
@@ -16,6 +16,10 @@ public class MakeProject implements ICOwner {
 		ext.setExtensionData("command", "make");
 	}
 
-	public void update(ICDescriptor cproject) {
+	public void update(ICDescriptor cproject, String extensionID) {
+		if ( extensionID.equals(CCorePlugin.BUILDER_MODEL_ID ) ) {
+			ICExtensionReference ext = cproject.create(CCorePlugin.BUILDER_MODEL_ID, CCorePlugin.getDefault().PLUGIN_ID + ".makeBuilder");
+			ext.setExtensionData("command", "make");
+		}
 	}
 }