diff --git a/Sources/MandelbrotEngine/MandelbrotSet.swift b/Sources/MandelbrotEngine/MandelbrotSet.swift
index f7c05ff..7299620 100644
--- a/Sources/MandelbrotEngine/MandelbrotSet.swift
+++ b/Sources/MandelbrotEngine/MandelbrotSet.swift
@@ -27,7 +27,7 @@ public struct MandelbrotSet {
     public var imageSize: (width: Int, height: Int)
 
 
-    public init(config: MandelbrotSetConfig, progress: Progress) {
+    public init(config: MandelbrotSetConfig, progress: Progress, timer: @escaping Timer.Action) {
         self.config = config
         let ys = Array(stride(from: config.yMin, to: config.yMax, by: config.dy))
         let xs = Array(stride(from: config.xMin, to: config.xMax, by: config.dx))
@@ -35,7 +35,7 @@ public struct MandelbrotSet {
         grid.reserveCapacity(xs.count * ys.count)
 
         let progressHelper = ProgressHelper(steps: imageSize.height, progress: progress)
-        let timerHelper = TimerHelper()
+        let timerHelper = Timer(action: timer)
 
         for (i, y) in ys.enumerated() {
             for x in xs {
diff --git a/Sources/MandelbrotEngine/TimerHelper.swift b/Sources/MandelbrotEngine/TimerHelper.swift
index 63b639b..847112d 100644
--- a/Sources/MandelbrotEngine/TimerHelper.swift
+++ b/Sources/MandelbrotEngine/TimerHelper.swift
@@ -9,11 +9,16 @@
 
 import Foundation
 
-struct TimerHelper {
+public struct Timer {
+    public typealias Action = (TimeInterval) -> Void
+
     private let nano = 1_000_000_000.0
     let start: DispatchTime
+    let action: Action
+
 
-    init() {
+    init(action: @escaping Action) {
+        self.action = action
         self.start = DispatchTime.now()
     }
 
@@ -21,6 +26,7 @@ struct TimerHelper {
     func end() {
         let e = DispatchTime.now()
         let dt = e.uptimeNanoseconds - start.uptimeNanoseconds
-        print(Double(dt) / nano)
+        let s = Double(dt) / nano
+        action(s)
     }
 }