diff --git a/lib/rules/no-unused-expressions.js b/lib/rules/no-unused-expressions.js
index 860737d..d31a074 100644
--- a/lib/rules/no-unused-expressions.js
+++ b/lib/rules/no-unused-expressions.js
@@ -255,11 +255,15 @@ module.exports = {
             return null;
         }
 
-
+        const sourceCode = context.sourceCode ?? context.getSourceCode();
         return {
             ExpressionStatement: function(node) {
                 var valid = !Checker.isDisallowed(node.expression)
-                    || isDirective(node, context.getAncestors())
+                    || isDirective(node,
+                        (sourceCode.getAncestors
+                            ? sourceCode.getAncestors(node)
+                            : context.getAncestors()
+                        ))
                     || isChaiExpectCall(node)
                     || isChaiShouldCall(node);
                 if (!valid) {