diff --git a/src/apis/watch.ts b/src/apis/watch.ts
index 83522aed..91f68c3f 100644
--- a/src/apis/watch.ts
+++ b/src/apis/watch.ts
@@ -341,7 +341,11 @@ function createWatcher(
   }
 
   const applyCb = (n: any, o: any) => {
-    if (isMultiSource && n.every((v: any, i: number) => Object.is(v, o[i])))
+    if (
+      !deep &&
+      isMultiSource &&
+      n.every((v: any, i: number) => Object.is(v, o[i]))
+    )
       return
     // cleanup before running cb again
     runCleanup()
diff --git a/test/v3/runtime-core/apiWatch.spec.ts b/test/v3/runtime-core/apiWatch.spec.ts
index d1f440a1..f71bcd05 100644
--- a/test/v3/runtime-core/apiWatch.spec.ts
+++ b/test/v3/runtime-core/apiWatch.spec.ts
@@ -572,4 +572,14 @@ describe('api: watch', () => {
     await nextTick()
     expect(dummy).toEqual([1, 2])
   })
+
+  // #805 #807
+  it('watching sources: [ref<[]>] w/ deep', async () => {
+    const foo = ref([1])
+    const cb = jest.fn()
+    watch([foo], cb, { deep: true })
+    foo.value.push(2)
+    await nextTick()
+    expect(cb).toBeCalledTimes(1)
+  })
 })