diff --git a/profile.php b/profile.php
index 8f1105b..531f5c6 100644
--- a/profile.php
+++ b/profile.php
@@ -196,7 +196,9 @@
 $data['lockreason'] = format_text($data['lockreason']);
 $tabs = new tabs($url);
 
-$data['lang'] = get_config('core', 'lang');
+// JavaScript locale string. Arguably "localecldr/langconfig" would be a better
+// choice, but it's not present in Totara langpacks.
+$data['locale'] = get_string('iso6391', 'langconfig');
 
 $data['course'] = helper::course_display_link($data['courseid']);
 
diff --git a/templates/flamegraph.mustache b/templates/flamegraph.mustache
index 988e344..cb733f4 100644
--- a/templates/flamegraph.mustache
+++ b/templates/flamegraph.mustache
@@ -27,12 +27,12 @@
 
     Context variables required for this template:
     * id - The id of the profile
-    * lang - Language setting
+    * locale - Language setting (a BCP 47 language tag)
 
     Example context (json):
     {
         "id" : 3,
-        "lang" : "en"
+        "locale" : "en"
     }
 }}
 
@@ -73,7 +73,7 @@ function displaysamplestats(d) {
     }
 
     const percentage = ((d.x1 - d.x0) * 100).toFixed(3);
-    const samplecount = d.value.toLocaleString("{{lang}}");
+    const samplecount = d.value.toLocaleString("{{locale}}");
 
     return d.data.name + ` (${percentage}%, ${samplecount} {{#str}} samples, tool_excimer {{/str}}, {{#str}} duration, tool_excimer {{/str}} ~ ${durationstr}})`;
 }
diff --git a/templates/memoryusagegraph.mustache b/templates/memoryusagegraph.mustache
index 766c41d..8eb2894 100644
--- a/templates/memoryusagegraph.mustache
+++ b/templates/memoryusagegraph.mustache
@@ -27,10 +27,12 @@
 
     Context variables required for this template:
     * id - The id of the profile
+    * locale - Language setting (a BCP 47 language tag)
 
     Example context (json):
     {
-        "id" : 3
+        "id" : 3,
+        "locale": "en"
     }
 }}
 
@@ -177,7 +179,7 @@ function processGraph(id, data) {
       .attr("cx", function(d) { return x(d.sampleindex); })
       .attr("cy", function(d) { return y(d.value); })
       .on("mouseover", function(event, d) {
-          const sampleindex = d.sampleindex.toLocaleString('{{lang}}');
+          const sampleindex = d.sampleindex.toLocaleString('{{locale}}');
           div.transition()
               .duration(200)
               .style("opacity", .9);