diff --git a/jasmine/jasmine.d.ts b/jasmine/jasmine.d.ts
index 9841a74fc8..5fd8b49f56 100644
--- a/jasmine/jasmine.d.ts
+++ b/jasmine/jasmine.d.ts
@@ -301,7 +301,7 @@ declare namespace jasmine {
         toContain(expected: any, expectationFailOutput?: any): boolean;
         toBeLessThan(expected: number, expectationFailOutput?: any): boolean;
         toBeGreaterThan(expected: number, expectationFailOutput?: any): boolean;
-        toBeCloseTo(expected: number, precision: any, expectationFailOutput?: any): boolean;
+        toBeCloseTo(expected: number, precision?: any, expectationFailOutput?: any): boolean;
         toThrow(expected?: any): boolean;
         toThrowError(message?: string | RegExp): boolean;
         toThrowError(expected?: new (...args: any[]) => Error, message?: string | RegExp): boolean;