diff --git a/compat/operator/first.ts b/compat/operator/first.ts
index 1ad45d503d..44d5655f78 100644
--- a/compat/operator/first.ts
+++ b/compat/operator/first.ts
@@ -1,6 +1,8 @@
 import { Observable } from 'rxjs';
 import { first as higherOrder } from 'rxjs/operators';
 
+export function first<T>(this: Observable<T>, predicate?: (value: T, index: number, source: Observable<T>) => boolean,
+                         defaultValue?: T): Observable<T>;
 /**
  * Emits only the first value (or the first value that meets some condition)
  * emitted by the source Observable.
@@ -44,7 +46,6 @@ import { first as higherOrder } from 'rxjs/operators';
  * @method first
  * @owner Observable
  */
-export function first<T>(this: Observable<T>, predicate?: (value: T, index: number, source: Observable<T>) => boolean,
-                         defaultValue?: T): Observable<T> {
-    return higherOrder(predicate, defaultValue)(this);
+export function first<T>(this: Observable<T>, ...args: any[]): Observable<T> {
+    return higherOrder<T>(...args)(this);
   }
diff --git a/compat/operator/last.ts b/compat/operator/last.ts
index 3133381a5c..c094aad61f 100644
--- a/compat/operator/last.ts
+++ b/compat/operator/last.ts
@@ -1,6 +1,8 @@
 import { Observable } from 'rxjs';
 import { last as higherOrder } from 'rxjs/operators';
 
+export function last<T>(this: Observable<T>, predicate?: (value: T, index: number, source: Observable<T>) => boolean,
+                        defaultValue?: T): Observable<T>;
 /**
  * Returns an Observable that emits only the last item emitted by the source Observable.
  * It optionally takes a predicate function as a parameter, in which case, rather than emitting
@@ -20,7 +22,6 @@ import { last as higherOrder } from 'rxjs/operators';
  * @method last
  * @owner Observable
  */
-export function last<T>(this: Observable<T>, predicate?: (value: T, index: number, source: Observable<T>) => boolean,
-                        defaultValue?: T): Observable<T> {
-  return higherOrder(predicate, defaultValue)(this);
+export function last<T>(this: Observable<T>, ...args: any[]): Observable<T> {
+  return higherOrder<T>(...args)(this);
 }