diff --git a/src/librustdoc/html/static/js/main.js b/src/librustdoc/html/static/js/main.js
index b475e6418a7..26639a85601 100644
--- a/src/librustdoc/html/static/js/main.js
+++ b/src/librustdoc/html/static/js/main.js
@@ -673,7 +673,6 @@ function preLoadCss(cssUrl) {
     }
 
     // <https://github.com/search?q=repo%3Arust-lang%2Frust+[RUSTDOCIMPL]+trait.impl&type=code>
-    // @ts-expect-error
     window.register_implementors = imp => {
         const implementors = document.getElementById("implementors-list");
         const synthetic_implementors = document.getElementById("synthetic-implementors-list");
@@ -765,9 +764,7 @@ function preLoadCss(cssUrl) {
             }
         }
     };
-    // @ts-expect-error
     if (window.pending_implementors) {
-        // @ts-expect-error
         window.register_implementors(window.pending_implementors);
     }
 
diff --git a/src/librustdoc/html/static/js/rustdoc.d.ts b/src/librustdoc/html/static/js/rustdoc.d.ts
index def0bd4f71e..4504642480b 100644
--- a/src/librustdoc/html/static/js/rustdoc.d.ts
+++ b/src/librustdoc/html/static/js/rustdoc.d.ts
@@ -44,6 +44,15 @@ declare global {
          * Set up event listeners for a scraped source example.
          */
         updateScrapedExample?: function(HTMLElement, HTMLElement),
+        /**
+         * register trait implementors, called by code generated in
+         * `write_shared.rs`
+         */
+        register_implementors?: function(Implementors): void,
+        /**
+         * fallback in case `register_implementors` isn't defined yet.
+         */
+        pending_implementors?: Implementors,
     }
     interface HTMLElement {
         /** Used by the popover tooltip code. */
@@ -415,4 +424,12 @@ declare namespace rustdoc {
     };
 
     type VlqData = VlqData[] | number;
+
+    /**
+     * Maps from crate names to trait implementation data.
+     * Provied by generated `trait.impl` files.
+     */
+    type Implementors = {
+        [key: string]: Array<[string, number, Array<string>]>
+    }
 }