diff --git a/static/js/details.js b/static/js/details.js
index cafaa6cf..1404091c 100644
--- a/static/js/details.js
+++ b/static/js/details.js
@@ -137,7 +137,7 @@ $(function () {
                 if (htmlPre.length) {
                     var opts = {USE_PROFILES: {html: true}};
                     var clean = DOMPurify.sanitize(htmlPre.text(), opts);
-                    var blob = new Blob([clean], {type: "text/html"});
+                    var blob = new Blob([clean], {type: "text/html; charset=utf-8"});
 
                     htmlPre.remove();
                     document.getElementById("email-body-html-iframe").src = URL.createObjectURL(blob);
diff --git a/static/js/log.js b/static/js/log.js
index 3b65cd50..1c34d21f 100644
--- a/static/js/log.js
+++ b/static/js/log.js
@@ -10,7 +10,7 @@ $(function () {
             if (htmlPre.length) {
                 var opts = {USE_PROFILES: {html: true}};
                 var clean = DOMPurify.sanitize(htmlPre.text(), opts);
-                var blob = new Blob([clean], {type: "text/html"});
+                var blob = new Blob([clean], {type: "text/html; charset=utf-8"});
 
                 htmlPre.remove();
                 document.getElementById("email-body-html-iframe").src = URL.createObjectURL(blob);