diff --git a/types/hirestime/hirestime-tests.ts b/types/hirestime/hirestime-tests.ts
index eb92c09203..b30c3cd88a 100644
--- a/types/hirestime/hirestime-tests.ts
+++ b/types/hirestime/hirestime-tests.ts
@@ -3,6 +3,9 @@ import hirestime = require("hirestime");
 const getElapsed = hirestime();
 
 let n: number = getElapsed();
-n = getElapsed(hirestime.S);
-n = getElapsed(hirestime.MS);
-n = getElapsed(hirestime.NS);
+n = getElapsed.s();
+n = getElapsed.seconds();
+n = getElapsed.ms();
+n = getElapsed.milliseconds();
+n = getElapsed.ns();
+n = getElapsed.nanoseconds();
diff --git a/types/hirestime/index.d.ts b/types/hirestime/index.d.ts
index 32d2b4e402..3268bac4dc 100644
--- a/types/hirestime/index.d.ts
+++ b/types/hirestime/index.d.ts
@@ -1,4 +1,4 @@
-// Type definitions for hirestime 3.2
+// Type definitions for hirestime 4.0
 // Project: https://github.com/seriousManual/hirestime
 // Definitions by: Junxiao Shi <https://github.com/yoursunny>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
@@ -6,12 +6,14 @@
 
 export = hirestime;
 
-declare namespace hirestime {
-    const S = "s";
-    const MS = "ms";
-    const NS = "ns";
+interface getElapsed {
+    (): number;
+    s(): number;
+    seconds(): number;
+    ms(): number;
+    milliseconds(): number;
+    ns(): number;
+    nanoseconds(): number;
 }
 
-type returnedFunction = (unit?: "s"|"ms"|"ns") => number;
-
-declare function hirestime(): returnedFunction;
+declare function hirestime(): getElapsed;