diff --git a/debug_toolbar/static/debug_toolbar/js/timer.js b/debug_toolbar/static/debug_toolbar/js/timer.js
index bb777ee10..a88ab0d15 100644
--- a/debug_toolbar/static/debug_toolbar/js/timer.js
+++ b/debug_toolbar/static/debug_toolbar/js/timer.js
@@ -5,15 +5,29 @@ function insertBrowserTiming() {
         timingEnd = performance.timing.loadEventEnd,
         totalTime = timingEnd - timingOffset;
     function getLeft(stat) {
-        return ((performance.timing[stat] - timingOffset) / totalTime) * 100.0;
+        if (totalTime !== 0) {
+            return (
+                ((performance.timing[stat] - timingOffset) / totalTime) * 100.0
+            );
+        } else {
+            return 0;
+        }
     }
     function getCSSWidth(stat, endStat) {
-        let width =
-            ((performance.timing[endStat] - performance.timing[stat]) /
-                totalTime) *
-            100.0;
-        // Calculate relative percent (same as sql panel logic)
-        width = (100.0 * width) / (100.0 - getLeft(stat));
+        let width = 0;
+        if (totalTime !== 0) {
+            width =
+                ((performance.timing[endStat] - performance.timing[stat]) /
+                    totalTime) *
+                100.0;
+        }
+        const denominator = 100.0 - getLeft(stat);
+        if (denominator !== 0) {
+            // Calculate relative percent (same as sql panel logic)
+            width = (100.0 * width) / denominator;
+        } else {
+            width = 0;
+        }
         return width < 1 ? "2px" : width + "%";
     }
     function addRow(tbody, stat, endStat) {
diff --git a/docs/changes.rst b/docs/changes.rst
index 5ca3a17a9..1cf12d344 100644
--- a/docs/changes.rst
+++ b/docs/changes.rst
@@ -4,6 +4,7 @@ Change log
 Pending
 -------
 
+* Added protection against division by 0 in timer.js
 * Auto-update History panel for JavaScript ``fetch`` requests.
 * Support `HTMX boosting <https://htmx.org/docs/#boosting/>`__ and
   re-rendering the toolbar after the DOM has been replaced. This reworks
@@ -11,7 +12,6 @@ Pending
   This means we'll have slightly slower performance, but it's easier
   to handle re-rendering the toolbar when the DOM has been replaced.
 
-
 3.7.0 (2022-09-25)
 ------------------