diff --git a/org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/classpath/RuntimeClasspathViewer.java b/org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/classpath/RuntimeClasspathViewer.java
index e4caeb9418..0ff61ed7de 100644
--- a/org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/classpath/RuntimeClasspathViewer.java
+++ b/org.eclipse.jdt.debug.ui/ui/org/eclipse/jdt/internal/debug/ui/classpath/RuntimeClasspathViewer.java
@@ -64,17 +64,7 @@ public class RuntimeClasspathViewer implements IClasspathViewer {
 
 		@Override
 		public void preferenceChange(PreferenceChangeEvent event) {
-			if (DebugUIPlugin.getStandardDisplay().getThread().equals(Thread.currentThread())) {
-				refresh(true);
-			} else {
-				DebugUIPlugin.getStandardDisplay().syncExec(new Runnable() {
-					@Override
-					public void run() {
-						refresh(true);
-					}
-				});
-			}
-
+			DebugUIPlugin.getStandardDisplay().asyncExec(() -> refresh(true));
 		}
 	};
 
@@ -395,6 +385,9 @@ public void setSelection(ISelection selection) {
 
 	@Override
 	public void refresh(Object entry) {
+		if (fTree.isDisposed()) {
+			return;
+		}
 		getTreeViewer().refresh();
 	}