diff --git a/packages/jsts/src/rules/S131/rule.ts b/packages/jsts/src/rules/S131/rule.ts
index e3f13f25f14..23371ca957f 100644
--- a/packages/jsts/src/rules/S131/rule.ts
+++ b/packages/jsts/src/rules/S131/rule.ts
@@ -140,6 +140,11 @@ export const rule: Rule.RuleModule = {
       ...decoratedSwitchExhaustivenessRule.meta?.messages,
     },
     schema: switchExhaustivenessRule.meta!.schema,
+    defaultOptions: [
+      {
+        considerDefaultExhaustiveForUnions: true,
+      },
+    ],
   }),
   create(context: Rule.RuleContext) {
     return mergeRules(
diff --git a/packages/jsts/src/rules/S131/unit.test.ts b/packages/jsts/src/rules/S131/unit.test.ts
index 576aa98d89b..049b35171ef 100644
--- a/packages/jsts/src/rules/S131/unit.test.ts
+++ b/packages/jsts/src/rules/S131/unit.test.ts
@@ -43,6 +43,18 @@ describe('S131', () => {
           case 'bar':
             break;
         }
+      `,
+        },
+        {
+          code: `
+        type  T = 'foo' | 'bar';
+        const x = 'foo' as T;
+        switch (x) {
+          case 'foo':
+            break;
+          default:
+            break;
+        }
       `,
         },
         {