diff --git a/extension/content/firebug/css/selectorPanel.js b/extension/content/firebug/css/selectorPanel.js
index 89cf5ed33a..4a1b6502b2 100644
--- a/extension/content/firebug/css/selectorPanel.js
+++ b/extension/content/firebug/css/selectorPanel.js
@@ -360,24 +360,34 @@ var SelectorTemplate = domplate(BaseRep,
 var WarningTemplate = domplate(Firebug.Rep,
 {
     noSelectionTag:
-        TR({"class": "selectbugWarning "},
+        TR({"class": "selectorWarning"},
             TD({"class": "selectionElement"}, Locale.$STR("css.selector.noSelection"))
         ),
 
     noSelectionResultsTag:
-        TR({"class": "selectbugWarning "},
+        TR({"class": "selectorWarning"},
             TD({"class": "selectionElement"}, Locale.$STR("css.selector.noSelectionResults"))
         ),
 
     selectErrorTag:
-        TR({"class": "selectbugWarning"},
+        TR({"class": "selectorWarning"},
             TD({"class": "selectionElement"}, Locale.$STR("css.selector.selectorError"))
         ),
 
     selectErrorTextTag:
-        TR({"class": "selectbugWarning"},
-            TD({"class": "selectionErrorText selectionElement"}, SPAN("$object"))
+        TR({"class": "selectorWarning"},
+            TD({"class": "selectionErrorText selectionElement"},
+                SPAN("$object|getErrorMessage")
+            )
         ),
+
+    getErrorMessage: function(object)
+    {
+        if (object.message)
+            return object.message;
+
+        return Locale.$STR("css.selector.unknownErrorMessage");
+    }
 });
 
 // ********************************************************************************************* //
diff --git a/extension/locale/en-US/firebug.properties b/extension/locale/en-US/firebug.properties
index 685313702d..7f00ca3f39 100644
--- a/extension/locale/en-US/firebug.properties
+++ b/extension/locale/en-US/firebug.properties
@@ -1674,3 +1674,7 @@ css.selector.Selection=Selection
 panel.tip.selector=Displays elements matching a CSS selector
 css.selector.TryASelector=Try a selector...
 
+# LOCALIZATION NOTE (css.selector.unknownErrorMessage): An error message displayed
+# to the user if querySelectorAll (used by the Selector side panel) fails and there is no
+# explanantion coming from the platform.
+css.selector.unknownErrorMessage=Failed to execute specified selector string
diff --git a/extension/skin/classic/selector.css b/extension/skin/classic/selector.css
index d248e10c2e..bbfb3b0e7f 100644
--- a/extension/skin/classic/selector.css
+++ b/extension/skin/classic/selector.css
@@ -1,4 +1,5 @@
-/* Rules for selectbug's Selector panel elements */
+/* Rules for Selector panel elements */
+
 .cssSelectionTable {
     width: 100%;
 }
@@ -6,7 +7,7 @@
     padding: 0 0 0 1ex;
 }
 
-.selectbugWarning {
+.selectorWarning {
     font-size: 11px;
     color: gray;
     padding: 2px 0 0 1ex;
@@ -18,7 +19,7 @@
     background-color: #FFEBEB;
 }
 
-/* Rules for selectbug's effect on CSS stylesheet panel */
+/* Rules for select panel's effect on CSS stylesheet panel */
 .selectedSelectorRule {
     border-color: Highlight !important;
     background-color: #EBF5FF !important;