diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CElementInfo.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CElementInfo.java
index 333c15e2ac0..c37308c8ec1 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CElementInfo.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/model/CElementInfo.java
@@ -94,6 +94,20 @@ class CElementInfo {
 		return fIsStructureKnown;
 	}
 
+	/**
+	 * @see ICElement.isStructureKnown()
+	 */
+	public boolean isReadOnly () {
+		try {
+			IResource r = getElement().getUnderlyingResource();
+			if (r != null) {
+				return r.isReadOnly();
+			}
+		} catch (CModelException e) {
+		}
+		return true;
+	}
+
 	/**
 	 * Returns an array with all the same elements as the specified array except for
 	 * the element to remove. Assumes that the deletion is contained in the array.