diff --git a/TS.fsx b/TS.fsx
index 95a1b7f8f..ebb327fd1 100644
--- a/TS.fsx
+++ b/TS.fsx
@@ -832,6 +832,7 @@ module Emit =
         Pt.Printl ""
 
     let EmitElementTagNameMap () =
+        Pt.Printl "/** @deprecated Directly use HTMLElementTagNameMap or SVGElementTagNameMap as appropriate, instead. */"
         Pt.Printl "interface ElementTagNameMap extends HTMLElementTagNameMap, SVGElementTagNameMap { }"
         Pt.Printl ""
 
diff --git a/baselines/dom.generated.d.ts b/baselines/dom.generated.d.ts
index 4b8e32b7b..70a0b90fe 100644
--- a/baselines/dom.generated.d.ts
+++ b/baselines/dom.generated.d.ts
@@ -15029,6 +15029,7 @@ interface SVGElementTagNameMap {
     "view": SVGViewElement;
 }
 
+/** @deprecated Directly use HTMLElementTagNameMap or SVGElementTagNameMap as appropriate, instead. */
 interface ElementTagNameMap extends HTMLElementTagNameMap, SVGElementTagNameMap { }
 
 declare var Audio: { new(src?: string): HTMLAudioElement; };