diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/ASTProvider.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/ASTProvider.java
index 110538f0fc5..25ae188afc6 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/ASTProvider.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/editor/ASTProvider.java
@@ -314,8 +314,7 @@ public final class ASTProvider {
 			PlatformUI.getWorkbench().removeWindowListener(fActivationListener);
 			fActivationListener= null;
 		}
-
-		fCache.disposeAST();
+		fCache.setActiveElement(null);
 	}
 
 	/*