diff --git a/src/main/java/org/opentripplanner/middleware/triptracker/TrackingLocation.java b/src/main/java/org/opentripplanner/middleware/triptracker/TrackingLocation.java
index e161a88aa..c31340863 100644
--- a/src/main/java/org/opentripplanner/middleware/triptracker/TrackingLocation.java
+++ b/src/main/java/org/opentripplanner/middleware/triptracker/TrackingLocation.java
@@ -1,6 +1,6 @@
 package org.opentripplanner.middleware.triptracker;
 
-import java.time.ZonedDateTime;
+import java.time.Instant;
 import java.util.Date;
 
 /**
@@ -39,9 +39,7 @@ public TrackingLocation(Double lat, Double lon, Date timestamp) {
     }
 
     /** Used in testing **/
-    public TrackingLocation(String dateTime, double lat, double lon) {
-        this.timestamp = new Date(ZonedDateTime.parse(dateTime).toInstant().toEpochMilli());
-        this.lat = lat;
-        this.lon = lon;
+    public TrackingLocation(Instant instant, double lat, double lon) {
+        this(lat, lon, new Date(instant.toEpochMilli()));
     }
 }
diff --git a/src/test/java/org/opentripplanner/middleware/controllers/api/ManageLegTraversalTest.java b/src/test/java/org/opentripplanner/middleware/controllers/api/ManageLegTraversalTest.java
index 30f4e9526..e9d27a2d7 100644
--- a/src/test/java/org/opentripplanner/middleware/controllers/api/ManageLegTraversalTest.java
+++ b/src/test/java/org/opentripplanner/middleware/controllers/api/ManageLegTraversalTest.java
@@ -24,9 +24,7 @@
 
 import java.io.IOException;
 import java.time.Instant;
-import java.time.ZoneId;
 import java.time.ZonedDateTime;
-import java.time.format.DateTimeFormatter;
 import java.time.temporal.ChronoUnit;
 import java.util.Date;
 import java.util.List;
@@ -68,9 +66,9 @@ public static void setUp() throws IOException {
 
     @ParameterizedTest
     @MethodSource("createTrace")
-    void canTrackTrip(String time, double lat, double lon, TripStatus expected, String message) {
+    void canTrackTrip(Instant instant, double lat, double lon, TripStatus expected, String message) {
         TrackedJourney trackedJourney = new TrackedJourney();
-        TrackingLocation trackingLocation = new TrackingLocation(time, lat, lon);
+        TrackingLocation trackingLocation = new TrackingLocation(instant, lat, lon);
         trackedJourney.locations = List.of(trackingLocation);
         TravelerPosition travelerPosition = new TravelerPosition(trackedJourney, busStopToJusticeCenterItinerary);
         TripStatus tripStatus = TripStatus.getTripStatus(travelerPosition);
@@ -93,51 +91,53 @@ private static Stream<Arguments> createTrace() {
             1000,
             calculateBearing(current.start, after.start)
         );
+        Instant startInstant = startTime.toInstant();
+        long currentSegmentStartOffsetSecs = (long) Math.floor(current.cumulativeTime - current.timeInSegment);
         return Stream.of(
             Arguments.of(
-                getDateTimeAsString(startTime, before.cumulativeTime - before.timeInSegment),
+                startInstant.plusSeconds((long) Math.floor(before.cumulativeTime - before.timeInSegment)),
                 current.start.lat,
                 current.start.lon,
                 TripStatus.AHEAD_OF_SCHEDULE,
                 "For the current location and time the traveler is ahead of schedule."
             ),
             Arguments.of(
-                getDateTimeAsString(startTime, current.cumulativeTime - current.timeInSegment),
+                startInstant.plusSeconds(currentSegmentStartOffsetSecs),
                 current.start.lat,
                 current.start.lon,
                 TripStatus.ON_SCHEDULE,
                 "For the current location and time the traveler is on schedule."
             ),
             Arguments.of(
-                getDateTimeAsString(startTime, after.cumulativeTime),
+                startInstant.plusSeconds((long) Math.floor(after.cumulativeTime)),
                 current.start.lat,
                 current.start.lon,
                 TripStatus.BEHIND_SCHEDULE,
                 "For the current location and time the traveler is behind schedule."
             ),
             Arguments.of(
-                getDateTimeAsString(startTime, (current.cumulativeTime - current.timeInSegment) - 10),
+                startInstant.plusSeconds(currentSegmentStartOffsetSecs - 10),
                 current.start.lat,
                 current.start.lon,
                 TripStatus.ON_SCHEDULE,
                 "For the current location and time (with a slight deviation) the traveler is on schedule."
             ),
             Arguments.of(
-                getDateTimeAsString(startTime, current.cumulativeTime),
+                startInstant.plusSeconds((long) Math.floor(current.cumulativeTime)),
                 current.start.lat + 0.00001,
                 current.start.lon + 0.00001,
                 TripStatus.ON_SCHEDULE,
                 "The current location, with a slight deviation, is on schedule."
             ),
             Arguments.of(
-                getDateTimeAsString(startTime, 0),
+                startInstant,
                 notOnTripCoordinates.lat,
                 notOnTripCoordinates.lon,
                 TripStatus.DEVIATED,
                 "Arbitrary lat/lon values which aren't on the trip leg."
             ),
             Arguments.of(
-                getDateTimeAsString(busStopToJusticeCenterItinerary.endTime, 1),
+                busStopToJusticeCenterItinerary.endTime.toInstant().plusSeconds(1),
                 deviatedCoordinates.lat,
                 deviatedCoordinates.lon,
                 TripStatus.DEVIATED,
@@ -422,12 +422,6 @@ private static List<LegSegment> createSegmentsForLeg() {
         return interpolatePoints(busStopToJusticeCenterItinerary.legs.get(0));
     }
 
-    private static String getDateTimeAsString(Date date, double offset) {
-        Instant dateTime = date.toInstant().plusSeconds((long) offset);
-        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'").withZone(ZoneId.systemDefault());;
-        return formatter.format(dateTime);
-    }
-
     private int getNumberOfExcludedPoints(List<Position> legPositions, Leg leg) {
         int excluded = 0;
         for (Position position : legPositions) {