diff --git a/src/components/script/dom/bindings/codegen/CodegenRust.py b/src/components/script/dom/bindings/codegen/CodegenRust.py
index d23dc062dab..47dda13927f 100644
--- a/src/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/src/components/script/dom/bindings/codegen/CodegenRust.py
@@ -1073,7 +1073,7 @@ class PropertyDefiner:
         specTemplate is a template for each entry of the spec array
 
         specTerminator is a terminator for the spec array (inserted at the end
-          of the array)
+          of the array), or None
 
         specType is the actual typename of our spec
 
@@ -1086,7 +1086,8 @@ class PropertyDefiner:
 
         for member in array:
             specs.append(specTemplate % getDataTuple(member))
-        specs.append(specTerminator)
+        if specTerminator:
+            specs.append(specTerminator)
 
         return (("static %s: [%s, ..%i] = [\n" +
                  ",\n".join(specs) + "\n" +
@@ -1254,7 +1255,7 @@ class ConstDefiner(PropertyDefiner):
         return decls + self.generatePrefableArray(
             array, name,
             '  ConstantSpec { name: &%s_name as *u8 as *libc::c_char, value: %s }',
-            '  ConstantSpec { name: 0 as *libc::c_char, value: VoidVal }',
+            None,
             'ConstantSpec',
             specData)
 
diff --git a/src/components/script/dom/bindings/utils.rs b/src/components/script/dom/bindings/utils.rs
index c7020823273..f6e9a1e1ba6 100644
--- a/src/components/script/dom/bindings/utils.rs
+++ b/src/components/script/dom/bindings/utils.rs
@@ -312,10 +312,8 @@ fn CreateInterfaceObject(cx: *mut JSContext, global: *mut JSObject, receiver: *m
 }
 
 fn DefineConstants(cx: *mut JSContext, obj: *mut JSObject, constants: &'static [ConstantSpec]) -> bool {
-    for spec in constants.iter() {
-        if spec.name.is_null() {
-            return true;
-        }
+    constants.iter().all(|spec| {
+        assert!(spec.name.is_not_null());
         let jsval = match spec.value {
             NullVal => NullValue(),
             IntVal(i) => Int32Value(i),
@@ -325,16 +323,11 @@ fn DefineConstants(cx: *mut JSContext, obj: *mut JSObject, constants: &'static [
             VoidVal => UndefinedValue(),
         };
         unsafe {
-            if JS_DefineProperty(cx, obj, spec.name,
-                                 jsval, None,
-                                 None,
-                                 JSPROP_ENUMERATE | JSPROP_READONLY |
-                                 JSPROP_PERMANENT) == 0 {
-                return false;
-            }
+            JS_DefineProperty(cx, obj, spec.name, jsval, None, None,
+                              JSPROP_ENUMERATE | JSPROP_READONLY |
+                              JSPROP_PERMANENT) != 0
         }
-    }
-    fail!();
+    })
 }
 
 fn DefineMethods(cx: *mut JSContext, obj: *mut JSObject, methods: &'static [JSFunctionSpec]) -> bool {