--- a/trychooser/index.html
+++ b/trychooser/index.html
@@ -260,17 +260,21 @@
                     <ul>OR
                     <li><label><input type="checkbox" value="mochitest-1">mochitest-1</label></li>
                     <li><label><input type="checkbox" value="mochitest-2">mochitest-2</label></li>
                     <li><label><input type="checkbox" value="mochitest-3">mochitest-3</label></li>
                     <li><label><input type="checkbox" value="mochitest-4">mochitest-4</label></li>
                     <li><label><input type="checkbox" value="mochitest-5">mochitest-5</label></li>
                     <li><label><input type="checkbox" value="mochitest-gl">mochitest-gl (webgl)</label></li>
                     <li><label><input type="checkbox" value="mochitest-bc">mochitest-bc (browser chrome)</label></li>
-                    <li><label><input type="checkbox" value="mochitest-browser-screenshots">mochitest-browser-screenshots</label></li>
+                    <li>
+                        <label id="mochitest-browser-screenshots" title="Requires the MOZSCREENSHOTS_SET environment variable to be specified">
+                            <input type="checkbox" value="mochitest-browser-screenshots">mochitest-browser-screenshots
+                        </label>
+                    </li>
                     <li><label><input type="checkbox" value="mochitest-dt">mochitest-dt (devtools)</label></li>
                     <li><label><input type="checkbox" value="mochitest-o">mochitest-o (other)</label></li>
                     <li><label><input type="checkbox" value="mochitest-media">mochitest-mda (dom/media)</label></li>
                     <li><label><input type="checkbox" value="mochitest-jetpack">mochitest-jetpack</label></li>
                     <li><label><input type="checkbox" value="mochitest-e10s-1">mochitest-e10s-1</label></li>
                     <li><label><input type="checkbox" value="mochitest-e10s-2">mochitest-e10s-2</label></li>
                     <li><label><input type="checkbox" value="mochitest-e10s-3">mochitest-e10s-3</label></li>
                     <li><label><input type="checkbox" value="mochitest-e10s-4">mochitest-e10s-4</label></li>

--- a/trychooser/trychooser.js
+++ b/trychooser/trychooser.js
@@ -243,19 +243,21 @@ function setresult() {
         $('#platforms-none').addClass('attention');
         incomplete = true;
     } else {
         $('#platforms-none').removeClass('attention');
     }
 
     if (value.match(/mochitest-browser-screenshots/) && !value.match(/MOZSCREENSHOTS_SETS=./)) {
         $('#setenv').addClass('attention');
+        $('#mochitest-browser-screenshots').addClass('attention');
         incomplete = true;
     } else {
         $('#setenv').removeClass('attention');
+        $('#mochitest-browser-screenshots').removeClass('attention');
     }
 
     if (incomplete) {
         value = "(NO JOBS CHOSEN)";
         $('.result').val(value);
     } else {
         $('#result_try').val('try: ' + value);
         $('#result_mach').val('./mach try ' + value);