diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
index 3341b86b986..b31af8cae35 100644
--- a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/language/settings/providers/AbstractBuiltinSpecsDetector.java
@@ -44,6 +44,7 @@ import org.eclipse.core.resources.IMarker;
 import org.eclipse.core.resources.IResource;
 import org.eclipse.core.resources.IWorkspaceRoot;
 import org.eclipse.core.resources.ResourcesPlugin;
+import org.eclipse.core.resources.WorkspaceJob;
 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IPath;
 import org.eclipse.core.runtime.IProgressMonitor;
@@ -350,9 +351,9 @@ public abstract class AbstractBuiltinSpecsDetector extends AbstractLanguageSetti
 		}
 		isExecuted = true;
 
-		Job job = new Job(ManagedMakeMessages.getResourceString("AbstractBuiltinSpecsDetector.DiscoverBuiltInSettingsJobName")) { //$NON-NLS-1$
+		WorkspaceJob job = new WorkspaceJob(ManagedMakeMessages.getResourceString("AbstractBuiltinSpecsDetector.DiscoverBuiltInSettingsJobName")) { //$NON-NLS-1$
 			@Override
-			protected IStatus run(IProgressMonitor monitor) {
+			public IStatus runInWorkspace(IProgressMonitor monitor) throws CoreException {
 				IStatus status;
 				try {
 					startup(currentCfgDescription, null);
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsProvidersSerializer.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsProvidersSerializer.java
index 5f7a2a65544..593e4c3ba8c 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsProvidersSerializer.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/language/settings/providers/LanguageSettingsProvidersSerializer.java
@@ -585,6 +585,7 @@ public class LanguageSettingsProvidersSerializer {
 			}
 		};
 
+		job.setRule(ResourcesPlugin.getWorkspace().getRoot());
 		job.schedule();
 	}