diff --git a/napi-inl.h b/napi-inl.h
index f8657ae..e7b02b2 100644
--- a/napi-inl.h
+++ b/napi-inl.h
@@ -1628,6 +1628,10 @@ inline uint8_t TypedArray::ElementSize() const {
     case napi_float32_array:
       return 4;
     case napi_float64_array:
+#if (NAPI_VERSION > 5)
+    case napi_bigint64_array:
+    case napi_biguint64_array:
+#endif  // (NAPI_VERSION > 5)
       return 8;
     default:
       return 0;