diff --git a/HealthImport/Model/WorkoutActivity+SQLite.swift b/HealthImport/Model/WorkoutActivity+SQLite.swift
index 8f3e3b8..28fffc3 100644
--- a/HealthImport/Model/WorkoutActivity+SQLite.swift
+++ b/HealthImport/Model/WorkoutActivity+SQLite.swift
@@ -1,5 +1,6 @@
 import Foundation
 import SQLite
+import HealthKit
 
 extension WorkoutActivity {
 
@@ -33,7 +34,7 @@ extension WorkoutActivity {
         try database.prepare(table).map(from)
     }
 
-    private static func from(row: Row) -> WorkoutActivity {
+    private static func from(row: Row) throws -> WorkoutActivity {
         .init(
             id: row[columnId],
             uuid: row[columnUUID],
@@ -41,7 +42,7 @@ extension WorkoutActivity {
             activityType: .init(rawValue: UInt(row[columnActivityType]))!,
             locationType: .init(rawValue: row[columnLocationType])!,
             swimmingLocationType: .init(rawValue: row[columnSwimmingLocationType])!,
-            lapLength: row[columnLapLength],
+            lapLength: try row[columnLapLength].map(lapLength),
             startDate: Date(timeIntervalSinceReferenceDate: row[columnStartDate]),
             endDate: Date(timeIntervalSinceReferenceDate: row[columnEndDate]),
             duration: row[columnDuration],
@@ -82,12 +83,22 @@ extension WorkoutActivity {
             columnActivityType <- Int(element.activityType.rawValue),
             columnLocationType <- element.locationType.rawValue,
             columnSwimmingLocationType <- element.swimmingLocationType.rawValue,
-            columnLapLength <- element.lapLength,
+            columnLapLength <- try element.lapLengthData(),
             columnStartDate <- element.startDate.timeIntervalSinceReferenceDate,
             columnEndDate <- element.endDate.timeIntervalSinceReferenceDate,
             columnDuration <- element.duration,
             columnMetadata <- element.metadata)
         )
     }
-
+}
+
+private extension WorkoutActivity {
+
+    func lapLengthData() throws -> Data? {
+        try lapLength.map { try NSKeyedArchiver.archivedData(withRootObject: $0, requiringSecureCoding: false) }
+    }
+
+    static func lapLength(from data: Data) throws -> HKQuantity? {
+        try NSKeyedUnarchiver.unarchivedObject(ofClass: HKQuantity.self, from: data)
+    }
 }
diff --git a/HealthImport/Model/WorkoutActivity.swift b/HealthImport/Model/WorkoutActivity.swift
index 6623431..37be2af 100644
--- a/HealthImport/Model/WorkoutActivity.swift
+++ b/HealthImport/Model/WorkoutActivity.swift
@@ -15,8 +15,8 @@ struct WorkoutActivity {
     
     let swimmingLocationType: HKWorkoutSwimmingLocationType
     
-    let lapLength: Data?
-    
+    let lapLength: HKQuantity?
+
     #warning("Fix timezone for dates")
     let startDate: Date
     
@@ -26,7 +26,7 @@ struct WorkoutActivity {
     
     let metadata: Data?
 
-    init(id: Int, uuid: Data, isPrimaryActivity: Bool, activityType: HKWorkoutActivityType, locationType: HKWorkoutSessionLocationType, swimmingLocationType: HKWorkoutSwimmingLocationType, lapLength: Data?, startDate: Date, endDate: Date, duration: TimeInterval, metadata: Data?) {
+    init(id: Int, uuid: Data, isPrimaryActivity: Bool, activityType: HKWorkoutActivityType, locationType: HKWorkoutSessionLocationType, swimmingLocationType: HKWorkoutSwimmingLocationType, lapLength: HKQuantity?, startDate: Date, endDate: Date, duration: TimeInterval, metadata: Data?) {
         self.id = id
         self.uuid = uuid
         self.isPrimaryActivity = isPrimaryActivity