diff --git a/src/server/utils/query/log-query.mocha.ts b/src/server/utils/query/log-query.mocha.ts
index 14c658360..8b9de8b3d 100644
--- a/src/server/utils/query/log-query.mocha.ts
+++ b/src/server/utils/query/log-query.mocha.ts
@@ -39,7 +39,7 @@ describe("log-query-info", () => {
   const expectedMessage = "Visualization query wiki_2016-04-29-12-40_2016-04-30-12-40";
   const expectedBasicVariables: Record<string, unknown> = {
     executionTime: 42,
-    startTime: 1461933600000,
+    startTime: "2016-04-29T12:40:00.000Z",
     startTimeMsAgo: 86391350,
     interval: 86400000,
     dataCube: "wiki",
@@ -65,7 +65,7 @@ describe("log-query-info", () => {
       {
         ...expectedBasicVariables,
         timeShift: "P1D",
-        shiftedStartTime: 1461847200000,
+        shiftedStartTime: "2016-04-28T12:40:00.000Z",
         shiftedStartTimeMsAgo: 172791350
       }
     )).to.be.true;
diff --git a/src/server/utils/query/log-query.ts b/src/server/utils/query/log-query.ts
index 168477dad..7ffc76ea8 100644
--- a/src/server/utils/query/log-query.ts
+++ b/src/server/utils/query/log-query.ts
@@ -45,7 +45,7 @@ function timeVariables(essence: Essence, timekeeper: Timekeeper): Record<string,
   const interval = clauseInterval(timeFilter);
 
   const variables: Record<string, unknown> = {
-    startTime: startTime.getTime(),
+    startTime: startTime.toISOString(),
     startTimeMsAgo: intervalLength(startTime, maxTime),
     interval
   };
@@ -57,7 +57,7 @@ function timeVariables(essence: Essence, timekeeper: Timekeeper): Record<string,
   if (essence.hasComparison()) {
     const previousTimeFilter = essence.previousTimeFilter(timekeeper);
     const shiftedStartTime = start(previousTimeFilter);
-    variables.shiftedStartTime = shiftedStartTime.getTime();
+    variables.shiftedStartTime = shiftedStartTime.toISOString();
     variables.shiftedStartTimeMsAgo = intervalLength(shiftedStartTime, maxTime);
     variables.timeShift = essence.timeShift.toString();
   }