diff --git a/packages/runtime-dom/__tests__/customElement.spec.ts b/packages/runtime-dom/__tests__/customElement.spec.ts
index dd087ad279d..6f8fd5012d1 100644
--- a/packages/runtime-dom/__tests__/customElement.spec.ts
+++ b/packages/runtime-dom/__tests__/customElement.spec.ts
@@ -232,7 +232,10 @@ describe('defineCustomElement', () => {
         emit('created')
         return () =>
           h('div', {
-            onClick: () => emit('my-click', 1)
+            onClick: () => {
+              emit('my-click', 1)
+              emit('myClick', 1) // validate hypenization
+            }
           })
       }
     })
@@ -252,10 +255,13 @@ describe('defineCustomElement', () => {
       const spy = jest.fn()
       e.addEventListener('my-click', spy)
       e.shadowRoot!.childNodes[0].dispatchEvent(new CustomEvent('click'))
-      expect(spy).toHaveBeenCalled()
+      expect(spy).toHaveBeenCalledTimes(2)
       expect(spy.mock.calls[0][0]).toMatchObject({
         detail: [1]
       })
+      expect(spy.mock.calls[1][0]).toMatchObject({
+        detail: [1]
+      })
     })
   })
 
diff --git a/packages/runtime-dom/src/apiCustomElement.ts b/packages/runtime-dom/src/apiCustomElement.ts
index 5108e3bdfbe..4a542c9ee27 100644
--- a/packages/runtime-dom/src/apiCustomElement.ts
+++ b/packages/runtime-dom/src/apiCustomElement.ts
@@ -354,7 +354,7 @@ export class VueElement extends BaseClass {
         // intercept emit
         instance.emit = (event: string, ...args: any[]) => {
           this.dispatchEvent(
-            new CustomEvent(event, {
+            new CustomEvent(hyphenate(event), {
               detail: args
             })
           )