diff --git a/bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/DirectoryDialog.java b/bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/DirectoryDialog.java
index 1cf25d6ce45..4df7269f17c 100644
--- a/bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/DirectoryDialog.java	
+++ b/bundles/org.eclipse.swt/Eclipse SWT/cocoa/org/eclipse/swt/widgets/DirectoryDialog.java	
@@ -195,7 +195,7 @@ public Optional<String> openDialog () {
 	directoryPath = null;
 	panel = NSOpenPanel.openPanel();
 	if (panel == null) {
-		return null;
+		throw new SWTException(SWT.ERROR_INVALID_RETURN_VALUE);
 	}
 
 	callback_performKeyEquivalent = new Callback(this, "_performKeyEquivalent", 3);