--- a/dom/animation/test/css-animations/test_animation-finish.html
+++ b/dom/animation/test/css-animations/test_animation-finish.html
@@ -2,14 +2,16 @@
 <meta charset=utf-8>
 <script src="/resources/testharness.js"></script>
 <script src="/resources/testharnessreport.js"></script>
 <div id="log"></div>
 <script>
 'use strict';
 setup({explicit_done: true});
 SpecialPowers.pushPrefEnv(
-  { "set": [["dom.animations-api.core.enabled", true]]},
+  { "set": [
+  	["dom.animations-api.core.enabled", true],
+  	["privacy.resistFingerprinting.reduceTimerPrecision.microseconds", 0]]},
   function() {
     window.open("file_animation-finish.html");
   });
 </script>
 </html>

--- a/toolkit/components/resistfingerprinting/tests/test_reduceprecision.cpp
+++ b/toolkit/components/resistfingerprinting/tests/test_reduceprecision.cpp
@@ -81,27 +81,27 @@ TEST(ResistFingerprinting, ReducePrecisi
   process(2601.64, nsRFPService::TimeScale::MilliSeconds, 20);
   process(2595.16, nsRFPService::TimeScale::MilliSeconds, 20);
   process(2578.66, nsRFPService::TimeScale::MilliSeconds, 20);
 }
 
 TEST(ResistFingerprinting, ReducePrecision_ExpectedLossOfPrecision) {
   double result;
   // We lose integer precision at 9007199254740992 - let's confirm that.
-  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740992, nsRFPService::TimeScale::MicroSeconds, 5);
-  ASSERT_EQ(result, 9007199254740990);
+  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740992.0, nsRFPService::TimeScale::MicroSeconds, 5);
+  ASSERT_EQ(result, 9007199254740990.0);
   // 9007199254740995 is approximated to 9007199254740996
-  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740995, nsRFPService::TimeScale::MicroSeconds, 5);
-  ASSERT_EQ(result, 9007199254740996);
+  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740995.0, nsRFPService::TimeScale::MicroSeconds, 5);
+  ASSERT_EQ(result, 9007199254740996.0);
   // 9007199254740999 is approximated as 9007199254741000
-  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740999, nsRFPService::TimeScale::MicroSeconds, 5);
-  ASSERT_EQ(result, 9007199254741000);
+  result = nsRFPService::ReduceTimePrecisionImpl(9007199254740999.0, nsRFPService::TimeScale::MicroSeconds, 5);
+  ASSERT_EQ(result, 9007199254741000.0);
   // 9007199254743568 can be represented exactly, but will be clamped to 9007199254743564
-  result = nsRFPService::ReduceTimePrecisionImpl(9007199254743568, nsRFPService::TimeScale::MicroSeconds, 5);
-  ASSERT_EQ(result, 9007199254743564);
+  result = nsRFPService::ReduceTimePrecisionImpl(9007199254743568.0, nsRFPService::TimeScale::MicroSeconds, 5);
+  ASSERT_EQ(result, 9007199254743564.0);
 }
 
 
 TEST(ResistFingerprinting, ReducePrecision_Expectations) {
   double result;
   result = nsRFPService::ReduceTimePrecisionImpl(2611.14, nsRFPService::TimeScale::MilliSeconds, 20);
   ASSERT_EQ(result, 2611.14);
   result = nsRFPService::ReduceTimePrecisionImpl(2611.145, nsRFPService::TimeScale::MilliSeconds, 20);
@@ -128,23 +128,23 @@ TEST(ResistFingerprinting, ReducePrecisi
      return;
   }
 
   for (int i=0; i<10000; i++) {
      // Test three different time magnitudes, with decimals.
      // Note that we need separate variables for the different units, as scaling
      // them after calculating them will erase effects of approximation.
      // A magnitude in the seconds since epoch range.
-     double time1_s = fmod(RAND_DOUBLE, 1516305819);
-     double time1_ms = fmod(RAND_DOUBLE, 1516305819000);
-     double time1_us = fmod(RAND_DOUBLE, 1516305819000000);
+     double time1_s = fmod(RAND_DOUBLE, 1516305819L);
+     double time1_ms = fmod(RAND_DOUBLE, 1516305819000L);
+     double time1_us = fmod(RAND_DOUBLE, 1516305819000000L);
      // A magnitude in the 'couple of minutes worth of milliseconds' range.
-     double time2_s = fmod(RAND_DOUBLE, (60 * 60 * 5));
-     double time2_ms = fmod(RAND_DOUBLE, (1000 * 60 * 60 * 5));
-     double time2_us = fmod(RAND_DOUBLE, (1000000 * 60 * 60 * 5));
+     double time2_s = fmod(RAND_DOUBLE, (60.0 * 60 * 5));
+     double time2_ms = fmod(RAND_DOUBLE, (1000.0 * 60 * 60 * 5));
+     double time2_us = fmod(RAND_DOUBLE, (1000000.0 * 60 * 60 * 5));
      // A magnitude in the small range.
      double time3_s = fmod(RAND_DOUBLE, 10);
      double time3_ms = fmod(RAND_DOUBLE, 10000);
      double time3_us = fmod(RAND_DOUBLE, 10000000);
 
      // Test two precision magnitudes, no decimals.
      // A magnitude in the high milliseconds.
      double precision1 = rand() % 250000;