diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/contentmergeviewer/TextMergeViewer.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/contentmergeviewer/TextMergeViewer.java
index e0ac759..b1db005 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/contentmergeviewer/TextMergeViewer.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/contentmergeviewer/TextMergeViewer.java
@@ -3011,8 +3011,10 @@
 				public IStatus runInUIThread(IProgressMonitor monitor) {
 					if (!getControl().isDisposed()) {
 						doDiff();
-						invalidateLines();
-						updateLines(doc);
+						if (!getControl().isDisposed()) { // doDiff() might have closed the editor
+							invalidateLines();
+							updateLines(doc);
+						}
 					}
 					return Status.OK_STATUS;
 				}