diff --git a/team/bundles/org.eclipse.compare/compare/org/eclipse/compare/structuremergeviewer/StructureDiffViewer.java b/team/bundles/org.eclipse.compare/compare/org/eclipse/compare/structuremergeviewer/StructureDiffViewer.java
index fd1da009312..0f1f3d0eb15 100644
--- a/team/bundles/org.eclipse.compare/compare/org/eclipse/compare/structuremergeviewer/StructureDiffViewer.java
+++ b/team/bundles/org.eclipse.compare/compare/org/eclipse/compare/structuremergeviewer/StructureDiffViewer.java
@@ -528,9 +528,11 @@ protected void diff() {
 			// A null compare configuration indicates that the viewer was disposed
 			if (compareConfiguration != null) {
 				compareConfiguration.getContainer().run(true, true, monitor -> {
-					monitor.beginTask(CompareMessages.StructureDiffViewer_2, 100);
-					diffTask.run(SubMonitor.convert(monitor, 100));
-					monitor.done();
+					try {
+						diffTask.run(SubMonitor.convert(monitor, CompareMessages.StructureDiffViewer_2, 100));
+					} finally {
+						monitor.done();
+					}
 				});
 			}
 		} catch (InvocationTargetException e) {