diff --git a/types/jasmine/index.d.ts b/types/jasmine/index.d.ts
index cc28931542..ed068f4775 100644
--- a/types/jasmine/index.d.ts
+++ b/types/jasmine/index.d.ts
@@ -122,7 +122,7 @@ declare function spyOn<T>(object: T, method: keyof T): jasmine.Spy;
  * @param property The name of the property to replace with a Spy
  * @param accessType The access type (get|set) of the property to Spy on.
  */
-declare function spyOnProperty<T>(object: T, property: keyof T, accessType: string): jasmine.Spy;
+declare function spyOnProperty<T>(object: T, property: keyof T, accessType?: 'get' | 'set'): jasmine.Spy;
 
 declare function runs(asyncMethod: Function): void;
 declare function waitsFor(latchMethod: () => boolean, failureMessage?: string, timeout?: number): void;
@@ -579,7 +579,7 @@ declare namespace jasmine {
         addBeforesAndAftersToQueue(): void;
         explodes(): void;
         spyOn(obj: any, methodName: string, ignoreMethodDoesntExist: boolean): Spy;
-        spyOnProperty(object: any, property: string, accessType: string): Spy;
+        spyOnProperty(object: any, property: string, accessType?: 'get' | 'set'): Spy;
         removeAllSpies(): void;
         throwOnExpectationFailure: boolean;
     }