diff --git a/index.d.ts b/index.d.ts
index 66cc58a..f4336b2 100644
--- a/index.d.ts
+++ b/index.d.ts
@@ -9,4 +9,7 @@ declare global {
   interface Window {
     IncludeFragmentElement: typeof IncludeFragmentElement
   }
-}
+  interface HTMLElementTagNameMap {
+    'include-fragment': IncludeFragmentElement
+  }
+}
\ No newline at end of file