diff --git a/TunnelKit/Sources/Core/Data+Manipulation.swift b/TunnelKit/Sources/Core/Data+Manipulation.swift
index c2779b6..faace91 100644
--- a/TunnelKit/Sources/Core/Data+Manipulation.swift
+++ b/TunnelKit/Sources/Core/Data+Manipulation.swift
@@ -203,7 +203,7 @@ extension Data {
 
 extension Array where Element == Data {
     var flatCount: Int {
-        return map { $0.count }.reduce(0) { $0 + $1 }
+        return reduce(0) { $0 + $1.count }
     }
 }
 
diff --git a/TunnelKitTests/Core/DataManipulationTests.swift b/TunnelKitTests/Core/DataManipulationTests.swift
index 14f987e..206650c 100644
--- a/TunnelKitTests/Core/DataManipulationTests.swift
+++ b/TunnelKitTests/Core/DataManipulationTests.swift
@@ -72,4 +72,14 @@ class DataManipulationTests: XCTestCase {
         XCTAssertEqual(z2.toData(), Data(hex: "5678ab"))
         XCTAssertEqual(z3.toData(), Data(hex: "5678abaaddcc"))
     }
+    
+    func testFlatCount() {
+        var v: [Data] = []
+        v.append(Data(hex: "11223344"))
+        v.append(Data(hex: "1122"))
+        v.append(Data(hex: "1122334455"))
+        v.append(Data(hex: "11223344556677"))
+        v.append(Data(hex: "112233"))
+        XCTAssertEqual(v.flatCount, 21)
+    }
 }