diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
index e5263bb11cfa..cef662266fb7 100644
--- a/dom/bindings/parser/WebIDL.py
+++ b/dom/bindings/parser/WebIDL.py
@@ -338,7 +338,10 @@ class IDLUnresolvedIdentifier(IDLObject):
 
         assert len(name) > 0
 
-        if name[:2] == "__" and name != "__content" and name != "___noSuchMethod__"  and not allowDoubleUnderscore:
+        if name == "__noSuchMethod__":
+            raise WebIDLError("__noSuchMethod__ is deprecated", [location])
+
+        if name[:2] == "__" and name != "__content" and not allowDoubleUnderscore:
             raise WebIDLError("Identifiers beginning with __ are reserved",
                               [location])
         if name[0] == '_' and not allowDoubleUnderscore:
@@ -3825,7 +3828,7 @@ class IDLMethod(IDLInterfaceMember, IDLScope):
         return self._hasOverloads
 
     def isIdentifierLess(self):
-        return self.identifier.name[:2] == "__" and self.identifier.name != "__noSuchMethod__"
+        return self.identifier.name[:2] == "__"
 
     def resolve(self, parentScope):
         assert isinstance(parentScope, IDLScope)
diff --git a/dom/bindings/parser/tests/test_method.py b/dom/bindings/parser/tests/test_method.py
index 43fa2828b664..f6f54c33ab6e 100644
--- a/dom/bindings/parser/tests/test_method.py
+++ b/dom/bindings/parser/tests/test_method.py
@@ -169,3 +169,16 @@ def WebIDLTest(parser, harness):
     except Exception, x:
         threw = True
     harness.ok(threw, "Should spell [Throws] correctly on methods")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            void __noSuchMethod__();
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow __noSuchMethod__ methods")