diff --git a/bundles/org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/PreviewWizardPage.java b/bundles/org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/PreviewWizardPage.java
index 95c263e4332..6d086c801b2 100644
--- a/bundles/org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/PreviewWizardPage.java
+++ b/bundles/org.eclipse.ltk.ui.refactoring/src/org/eclipse/ltk/internal/ui/refactoring/PreviewWizardPage.java
@@ -673,7 +673,9 @@ private void showPreview(PreviewNode element) {
 						if (container != null) {
 							if (newViewer.getControl() instanceof IAdaptable adaptable) {
 								CompareConfiguration config = adaptable.getAdapter(CompareConfiguration.class);
-								config.setContainer(new WizardCompareContainer(container));
+								if (config != null) {
+									config.setContainer(new WizardCompareContainer(container));
+								}
 							}
 						}
 					} else {