diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/PathEntryContainerUpdatesOperation.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/PathEntryContainerUpdatesOperation.java
index e0492ae4114..448a8d79795 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/PathEntryContainerUpdatesOperation.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/PathEntryContainerUpdatesOperation.java
@@ -33,6 +33,14 @@ public class PathEntryContainerUpdatesOperation extends CModelOperation {
 		this.container = container;
 		this.events = events;
 	}
+
+	/* (non-Javadoc)
+	 * @see org.eclipse.cdt.internal.core.model.CModelOperation#isReadOnly()
+	 */
+	public boolean isReadOnly() {
+		return true;
+	}
+
 	protected void executeOperation() throws CModelException {
 		PathEntryManager pathEntryManager = PathEntryManager.getDefault();
 		ArrayList list = new ArrayList(events.length);
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/SetPathEntryContainerOperation.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/SetPathEntryContainerOperation.java
index 5ab36322c05..6d5ebddadaa 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/SetPathEntryContainerOperation.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/SetPathEntryContainerOperation.java
@@ -33,6 +33,13 @@ public class SetPathEntryContainerOperation extends CModelOperation {
 		fPathEntryManager = PathEntryManager.getDefault();
 	}
 
+	/* (non-Javadoc)
+	 * @see org.eclipse.cdt.internal.core.model.CModelOperation#isReadOnly()
+	 */
+	public boolean isReadOnly() {
+		return true;
+	}
+
 	protected void executeOperation() throws CModelException {
 		if (isCanceled()) {
 			return;