--- a/devtools/server/actors/utils/TabSources.js
+++ b/devtools/server/actors/utils/TabSources.js
@@ -298,17 +298,19 @@ TabSources.prototype = {
     // script element, or does not have a src attribute.
     let element = aSource.element ? aSource.element.unsafeDereference() : null;
     if (element && (element.tagName !== "SCRIPT" || !element.hasAttribute("src"))) {
       spec.isInlineSource = true;
     } else {
       if (url) {
         // There are a few special URLs that we know are JavaScript:
         // inline `javascript:` and code coming from the console
-        if (url.indexOf("javascript:") === 0 || url === 'debugger eval code') {
+        if (url.indexOf("Scratchpad/") === 0 ||
+            url.indexOf("javascript:") === 0 ||
+            url === "debugger eval code") {
           spec.contentType = "text/javascript";
         } else {
           try {
             let pathname = new URL(url).pathname;
             let filename = pathname.slice(pathname.lastIndexOf("/") + 1);
             let index = filename.lastIndexOf(".");
             let extension = index >= 0 ? filename.slice(index + 1) : "";
             if (extension === "xml") {