--- a/testing/marionette/harness/marionette_harness/tests/unit/test_accessibility.py
+++ b/testing/marionette/harness/marionette_harness/tests/unit/test_accessibility.py
@@ -71,17 +71,17 @@ class TestAccessibility(MarionetteTestCa
         # manipulated by it
         "button9",
         # Element is not currently visible
         "button10"
     ]
 
     displayed_elementIDs = [
         "button1", "button2", "button3", "button4", "button5", "button6",
-        "button9", "no_accessible_but_displayed"
+        "no_accessible_but_displayed"
     ]
 
     displayed_but_a11y_hidden_elementIDs = ["button7", "button8"]
 
     disabled_elementIDs = ["button11", "no_accessible_but_disabled"]
 
     # Elements that are enabled but otherwise disabled or not explorable
     # via the accessibility API