diff --git a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/core/tests/ManagedProjectUpdateTests.java b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/core/tests/ManagedProjectUpdateTests.java
index b91e43b1311..df084c92385 100644
--- a/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/core/tests/ManagedProjectUpdateTests.java
+++ b/build/org.eclipse.cdt.managedbuilder.core.tests/tests/org/eclipse/cdt/managedbuilder/core/tests/ManagedProjectUpdateTests.java
@@ -20,15 +20,24 @@ import junit.framework.TestSuite;
 
 import org.eclipse.cdt.managedbuilder.core.IManagedBuildInfo;
 import org.eclipse.cdt.managedbuilder.core.ManagedBuildManager;
+import org.eclipse.cdt.managedbuilder.core.ManagedBuilderCorePlugin;
+import org.eclipse.cdt.managedbuilder.internal.core.ManagedMakeMessages;
 import org.eclipse.cdt.managedbuilder.projectconverter.UpdateManagedProjectManager;
 import org.eclipse.cdt.managedbuilder.testplugin.CTestPlugin;
 import org.eclipse.cdt.managedbuilder.testplugin.ManagedBuildTestHelper;
 import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.IWorkspace;
 import org.eclipse.core.resources.IncrementalProjectBuilder;
+import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.OperationCanceledException;
 import org.eclipse.core.runtime.Path;
+import org.eclipse.core.runtime.Status;
+import org.eclipse.core.runtime.jobs.ISchedulingRule;
+import org.eclipse.core.runtime.jobs.Job;
 import org.eclipse.ui.dialogs.IOverwriteQuery;
 
 public class ManagedProjectUpdateTests extends TestCase {
@@ -112,7 +121,7 @@ public class ManagedProjectUpdateTests extends TestCase {
 		if(projects == null || projects.length == 0)
 			return;
 		for(int i = 0; i < projects.length; i++){
-			IProject curProject = projects[i];
+			final IProject curProject = projects[i];
 			
 			//the project conversion occures the first time 
 			//ManagedBuildManager.getBuildInfo gets called
@@ -137,16 +146,40 @@ public class ManagedProjectUpdateTests extends TestCase {
 				}
 
 				//check whether the project builds without errors
-				try{
-					curProject.build(IncrementalProjectBuilder.INCREMENTAL_BUILD,null);
-				}
-				catch(CoreException e){
-					fail(e.getStatus().getMessage());
-				}
-				catch(OperationCanceledException e){
-					fail("the project \"" + curProject.getName() + "\" build was cancelled, exception message: " + e.getMessage());
+				IWorkspace wsp = ResourcesPlugin.getWorkspace();
+				ISchedulingRule rule = wsp.getRuleFactory().buildRule();
+				Job buildJob = new Job("project build job"){ 	//$NON-NLS-1$
+					protected IStatus run(IProgressMonitor monitor) {
+						try {
+							curProject.build(IncrementalProjectBuilder.INCREMENTAL_BUILD,null);
+						} catch(CoreException e){
+							fail(e.getStatus().getMessage());
+						} catch(OperationCanceledException e){
+							fail("the project \"" + curProject.getName() + "\" build was cancelled, exception message: " + e.getMessage());
+						}
+						return new Status(
+								IStatus.OK,
+								"org.eclipse.cdt.managedbuilder.core.tests",
+								IStatus.OK,
+								new String(),
+								null);
+					}
+				};
+				buildJob.setRule(rule);
+				
+				buildJob.schedule();
+				
+				try {
+					buildJob.join();
+				} catch (InterruptedException e) {
+					fail("the build job for the project \"" + curProject.getName() + "\" was interrupted, exception message: " + e.getMessage());
 				}
 				
+				IStatus status = buildJob.getResult();
+				if(status.getCode() != IStatus.OK){
+					fail("the build job for the project \"" + curProject.getName() + "\" failed, status message: " + status.getMessage());
+				}
+
 				//compare the generated makefiles to their benchmarks
 				if (files != null && files.length > 0) {
 					if (i == 0) {
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/projectconverter/UpdateManagedProject21.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/projectconverter/UpdateManagedProject21.java
index 7306014e7a6..34e5f7ad982 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/projectconverter/UpdateManagedProject21.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/projectconverter/UpdateManagedProject21.java
@@ -20,20 +20,22 @@ import org.eclipse.cdt.managedbuilder.internal.core.ManagedBuildInfo;
 import org.eclipse.core.resources.IFile;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IResourceProxy;
+import org.eclipse.core.resources.IResourceProxyVisitor;
 import org.eclipse.core.resources.IWorkspace;
 import org.eclipse.core.resources.IWorkspaceRunnable;
 import org.eclipse.core.resources.ProjectScope;
 import org.eclipse.core.resources.WorkspaceJob;
-import org.eclipse.core.runtime.jobs.MultiRule;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;
 import org.eclipse.core.runtime.IStatus;
-import org.eclipse.core.runtime.Status;
-import org.eclipse.core.runtime.jobs.ISchedulingRule;
 import org.eclipse.core.runtime.Platform;
+import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.content.IContentType;
 import org.eclipse.core.runtime.content.IContentTypeManager;
 import org.eclipse.core.runtime.content.IContentTypeSettings;
+import org.eclipse.core.runtime.jobs.ISchedulingRule;
+import org.eclipse.core.runtime.jobs.MultiRule;
 import org.eclipse.core.runtime.preferences.IScopeContext;
 
 class UpdateManagedProject21 {
@@ -112,28 +114,45 @@ class UpdateManagedProject21 {
 					};
 					workspace.run(runnable, project, IWorkspace.AVOID_UPDATE, monitor);
 				} catch (Exception e) {}	// Ignore the error - the user may have to add .c extensions to
-								// the local definition of C++ file extensions				
-				IResource[] files = project.members(IProject.EXCLUDE_DERIVED);
-				for (int i=0; i<files.length; i++) {
-					String ext = files[i].getFileExtension();
-					if (ext != null && ext.equals("c")) {						//$NON-NLS-1$
-						IContentTypeManager manager = Platform.getContentTypeManager();
-						IContentType contentType = manager.getContentType("org.eclipse.cdt.core.cxxSource");	//$NON-NLS-1$
-						IScopeContext projectScope = new ProjectScope(project);
-						IContentTypeSettings settings = contentType.getSettings(projectScope);
-						// First, copy the extensions from the "global" content type
-						String[] specs = contentType.getFileSpecs(IContentType.FILE_EXTENSION_SPEC);
-						for (int j = 0; j < specs.length; j++) {
-							settings.addFileSpec(specs[j], IContentType.FILE_EXTENSION_SPEC);
+								// the local definition of C++ file extensions
+				
+				final boolean found[] = new boolean[1];
+				project.accept(new IResourceProxyVisitor(){
+
+						/* (non-Javadoc)
+						 * @see org.eclipse.core.resources.IResourceProxyVisitor#visit(org.eclipse.core.resources.IResourceProxy)
+						 */
+						public boolean visit(IResourceProxy proxy) throws CoreException {
+							if(found[0] || proxy.isDerived())
+								return false;
+							if(proxy.getType() == IResource.FILE){
+								String ext = proxy.requestFullPath().getFileExtension();
+								if (ext != null && "c".equals(ext)) { //$NON-NLS-1$
+									found[0] = true;
+								}
+								return false;
+							}
+							return true;
 						}
-						specs = contentType.getFileSpecs(IContentType.FILE_NAME_SPEC);
-						for (int j = 0; j < specs.length; j++) {
-							settings.addFileSpec(specs[j], IContentType.FILE_NAME_SPEC);
-						}				
-						// Add the .c extension
-						settings.addFileSpec("c", IContentType.FILE_EXTENSION_SPEC);	//$NON-NLS-1$
-						break;
+					},
+					IResource.NONE);
+				
+				if(found[0]){
+					IContentTypeManager manager = Platform.getContentTypeManager();
+					IContentType contentType = manager.getContentType("org.eclipse.cdt.core.cxxSource");	//$NON-NLS-1$
+					IScopeContext projectScope = new ProjectScope(project);
+					IContentTypeSettings settings = contentType.getSettings(projectScope);
+					// First, copy the extensions from the "global" content type
+					String[] specs = contentType.getFileSpecs(IContentType.FILE_EXTENSION_SPEC);
+					for (int j = 0; j < specs.length; j++) {
+						settings.addFileSpec(specs[j], IContentType.FILE_EXTENSION_SPEC);
 					}
+					specs = contentType.getFileSpecs(IContentType.FILE_NAME_SPEC);
+					for (int j = 0; j < specs.length; j++) {
+						settings.addFileSpec(specs[j], IContentType.FILE_NAME_SPEC);
+					}				
+					// Add the .c extension
+					settings.addFileSpec("c", IContentType.FILE_EXTENSION_SPEC);	//$NON-NLS-1$
 				}
 			} catch (CoreException e) {
 				// Ignore errors.  User will need to manually add .c extension if necessary