diff --git a/browser/components/resistfingerprinting/test/browser/browser_performanceAPI.js b/browser/components/resistfingerprinting/test/browser/browser_performanceAPI.js
index 90b4b81710fc..a89fd169d951 100644
--- a/browser/components/resistfingerprinting/test/browser/browser_performanceAPI.js
+++ b/browser/components/resistfingerprinting/test/browser/browser_performanceAPI.js
@@ -37,10 +37,15 @@ let isRounded = (x, expectedPrecision) => {
     return true;
 
   // When we're diving by non-whole numbers, we may not get perfect
-  // multiplication/division because of floating points
-  if (Math.abs(rounded - x + expectedPrecision) < .0000001) {
+  // multiplication/division because of floating points.
+  // When dealing with ms since epoch, a double's precision is on the order
+  // of 1/5 of a microsecond, so we use a value a little higher than that as
+  // our epsilon.
+  // To be clear, this error is introduced in our re-calculation of 'rounded'
+  // above in JavaScript.
+  if (Math.abs(rounded - x + expectedPrecision) < .0005) {
     return true;
-  } else if (Math.abs(rounded - x) < .0000001) {
+  } else if (Math.abs(rounded - x) < .0005) {
     return true;
   }
 
diff --git a/browser/components/resistfingerprinting/test/browser/file_workerPerformance.js b/browser/components/resistfingerprinting/test/browser/file_workerPerformance.js
index 1791e015af1e..132accc5951c 100644
--- a/browser/components/resistfingerprinting/test/browser/file_workerPerformance.js
+++ b/browser/components/resistfingerprinting/test/browser/file_workerPerformance.js
@@ -17,10 +17,15 @@ let isRounded = (x, expectedPrecision) => {
     return true;
 
   // When we're diving by non-whole numbers, we may not get perfect
-  // multiplication/division because of floating points
-  if (Math.abs(rounded - x + expectedPrecision) < .0000001) {
+  // multiplication/division because of floating points.
+  // When dealing with ms since epoch, a double's precision is on the order
+  // of 1/5 of a microsecond, so we use a value a little higher than that as
+  // our epsilon.
+  // To be clear, this error is introduced in our re-calculation of 'rounded'
+  // above in JavaScript.
+  if (Math.abs(rounded - x + expectedPrecision) < .0005) {
     return true;
-  } else if (Math.abs(rounded - x) < .0000001) {
+  } else if (Math.abs(rounded - x) < .0005) {
     return true;
   }
 
diff --git a/browser/components/resistfingerprinting/test/mochitest/file_animation_api.html b/browser/components/resistfingerprinting/test/mochitest/file_animation_api.html
index 789afecbe94f..9c4ecdce1fb8 100644
--- a/browser/components/resistfingerprinting/test/mochitest/file_animation_api.html
+++ b/browser/components/resistfingerprinting/test/mochitest/file_animation_api.html
@@ -36,10 +36,15 @@
         return true;
 
       // When we're diving by non-whole numbers, we may not get perfect
-      // multiplication/division because of floating points
-      if (Math.abs(rounded - x + expectedPrecision) < .0000001) {
+      // multiplication/division because of floating points.
+      // When dealing with ms since epoch, a double's precision is on the order
+      // of 1/5 of a microsecond, so we use a value a little higher than that as
+      // our epsilon.
+      // To be clear, this error is introduced in our re-calculation of 'rounded'
+      // above in JavaScript.
+      if (Math.abs(rounded - x + expectedPrecision) < .0005) {
         return true;
-      } else if (Math.abs(rounded - x) < .0000001) {
+      } else if (Math.abs(rounded - x) < .0005) {
         return true;
       }
 
diff --git a/browser/components/resistfingerprinting/test/mochitest/test_reduce_time_precision.html b/browser/components/resistfingerprinting/test/mochitest/test_reduce_time_precision.html
index 319d3fda4c65..4ad80fde8568 100644
--- a/browser/components/resistfingerprinting/test/mochitest/test_reduce_time_precision.html
+++ b/browser/components/resistfingerprinting/test/mochitest/test_reduce_time_precision.html
@@ -50,13 +50,18 @@ https://trac.torproject.org/projects/tor/ticket/1517
     if (rounded === x || x === 0)
       return true;
 
-    // When we're diving by non-whole numbers, we may not get perfect
-    // multiplication/division because of floating points
-    if (Math.abs(rounded - x + expectedPrecision) < .0000001) {
-      return true;
-    } else if (Math.abs(rounded - x) < .0000001) {
-      return true;
-    }
+  // When we're diving by non-whole numbers, we may not get perfect
+  // multiplication/division because of floating points.
+  // When dealing with ms since epoch, a double's precision is on the order
+  // of 1/5 of a microsecond, so we use a value a little higher than that as
+  // our epsilon.
+  // To be clear, this error is introduced in our re-calculation of 'rounded'
+  // above in JavaScript.
+  if (Math.abs(rounded - x + expectedPrecision) < .0005) {
+    return true;
+  } else if (Math.abs(rounded - x) < .0005) {
+    return true;
+  }
 
     // Then we handle the case where you're sub-millisecond and the timer is not
     // We check that the timer is not sub-millisecond by assuming it is not if it