diff --git a/packages/inferno/src/DOM/events/delegation.ts b/packages/inferno/src/DOM/events/delegation.ts
index 12cbb5657..fbe47cb72 100644
--- a/packages/inferno/src/DOM/events/delegation.ts
+++ b/packages/inferno/src/DOM/events/delegation.ts
@@ -202,7 +202,6 @@ function attachEventToDocument(
       ? rootClickEvent(name)
       : rootEvent(name);
 
-  // @ts-expect-error TODO: FIXME
   document.addEventListener(normalizeEventName(name), attachedEvent);
 
   return attachedEvent;
diff --git a/packages/inferno/src/core/types.ts b/packages/inferno/src/core/types.ts
index a4f25ec2d..7d76efed5 100644
--- a/packages/inferno/src/core/types.ts
+++ b/packages/inferno/src/core/types.ts
@@ -79,8 +79,8 @@ export interface SemiSyntheticEvent<T> extends Event {
    * A reference to the element on which the event listener is registered.
    */
   currentTarget: EventTarget & T;
-  isDefaultPrevented: () => boolean;
-  isPropagationStopped: () => boolean;
+  isDefaultPrevented?: () => boolean;
+  isPropagationStopped?: () => boolean;
 }
 
 export type ClipboardEvent<T> = SemiSyntheticEvent<T> & NativeClipboardEvent;