diff --git a/locales/en-US/app.ftl b/locales/en-US/app.ftl
index 336411c89d..22fb583dfc 100644
--- a/locales/en-US/app.ftl
+++ b/locales/en-US/app.ftl
@@ -1195,9 +1195,12 @@ SourceView--close-button =
 ## The string IDs here currently all start with SourceView for historical reasons.
 
 # Displayed below SourceView--cannot-obtain-source, if the profiler does not
-# know which URL to request source code from.
-SourceView--no-known-cors-url =
-    There is no known cross-origin-accessible URL for this file.
+# know which URL to request source code from. This can happen for JavaScript
+# files when the "JavaScript Sources" feature is not enabled.
+SourceView--no-known-cors-url1 =
+    There is no known cross-origin-accessible URL for this file. If this is a
+    JavaScript file, you may need to enable the “JavaScript Sources” feature in
+    about:profiling.
 
 # Displayed below SourceView--cannot-obtain-source, if there was a network error
 # when fetching the source code for a file.
diff --git a/src/components/app/CodeErrorOverlay.tsx b/src/components/app/CodeErrorOverlay.tsx
index 29d3dfa0d4..e05e98311b 100644
--- a/src/components/app/CodeErrorOverlay.tsx
+++ b/src/components/app/CodeErrorOverlay.tsx
@@ -17,7 +17,7 @@ export function CodeErrorOverlay({ errors }: CodeErrorOverlayProps) {
         switch (error.type) {
           case 'NO_KNOWN_CORS_URL': {
             return (
-              <Localized key={key} id="SourceView--no-known-cors-url">
+              <Localized key={key} id="SourceView--no-known-cors-url1">
                 <li>No known cross-origin-accessible URL.</li>
               </Localized>
             );