diff --git a/servo/src/components/script/dom/bindings/codegen/CodegenRust.py b/servo/src/components/script/dom/bindings/codegen/CodegenRust.py
index 5da64c1c3d8c..27e7e344dfab 100644
--- a/servo/src/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/servo/src/components/script/dom/bindings/codegen/CodegenRust.py
@@ -3547,10 +3547,10 @@ return box_;""" % self.descriptor.concreteType)
 class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
     def __init__(self, descriptor):
         args = [Argument('*mut JSContext', 'cx'), Argument('*mut JSObject', 'proxy'),
-                Argument('jsid', 'id'), Argument('JSBool', 'set'),
+                Argument('jsid', 'id'), Argument('bool', 'set'),
                 Argument('*mut JSPropertyDescriptor', 'desc')]
         CGAbstractExternMethod.__init__(self, descriptor, "getOwnPropertyDescriptor",
-                                        "JSBool", args)
+                                        "bool", args)
         self.descriptor = descriptor
     def getBody(self):
         indexedGetter = self.descriptor.operations['IndexedGetter']
@@ -3562,7 +3562,7 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
 
         if indexedGetter:
             readonly = toStringBool(self.descriptor.operations['IndexedSetter'] is None)
-            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn 1;" % readonly
+            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn true;" % readonly
             templateValues = {'jsvalRef': '(*desc).value', 'successCode': fillDescriptor}
             get = ("if index.is_some() {\n" +
                    "  let index = index.unwrap();\n" +
@@ -3581,7 +3581,7 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
                     # FIXME need to check that this is a 'supported property index'
                     assert False
                 setOrIndexedGet += ("    FillPropertyDescriptor(&mut *desc, proxy, false);\n" +
-                                    "    return 1;\n" +
+                                    "    return true;\n" +
                                     "  }\n")
             if self.descriptor.operations['NamedSetter']:
                 setOrIndexedGet += "  if RUST_JSID_IS_STRING(id) {\n"
@@ -3589,7 +3589,7 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
                     # FIXME need to check that this is a 'supported property name'
                     assert False
                 setOrIndexedGet += ("    FillPropertyDescriptor(&mut *desc, proxy, false);\n" +
-                                    "    return 1;\n" +
+                                    "    return true;\n" +
                                     "  }\n")
             setOrIndexedGet += "}"
             if indexedGetter:
@@ -3598,20 +3598,20 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
                                     "}")
             setOrIndexedGet += "\n\n"
         elif indexedGetter:
-            setOrIndexedGet += ("if set == 0 {\n" +
+            setOrIndexedGet += ("if !set {\n" +
                                 CGIndenter(CGGeneric(get)).define() +
                                 "}\n\n")
 
         namedGetter = self.descriptor.operations['NamedGetter']
         if namedGetter:
             readonly = toStringBool(self.descriptor.operations['NamedSetter'] is None)
-            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn 1;" % readonly
+            fillDescriptor = "FillPropertyDescriptor(&mut *desc, proxy, %s);\nreturn true;" % readonly
             templateValues = {'jsvalRef': '(*desc).value', 'successCode': fillDescriptor}
             # Once we start supporting OverrideBuiltins we need to make
             # ResolveOwnProperty or EnumerateOwnProperties filter out named
             # properties that shadow prototype properties.
             namedGet = ("\n" +
-                        "if set == 0 && RUST_JSID_IS_STRING(id) != 0 && !HasPropertyOnPrototype(cx, proxy, id) {\n" +
+                        "if !set && RUST_JSID_IS_STRING(id) != 0 && !HasPropertyOnPrototype(cx, proxy, id) {\n" +
                         "  let name = jsid_to_str(cx, id);\n" +
                         "  let this = UnwrapProxy(proxy);\n" +
                         "  let this = JS::from_raw(this);\n" +
@@ -3624,19 +3624,19 @@ class CGDOMJSProxyHandler_getOwnPropertyDescriptor(CGAbstractExternMethod):
         return setOrIndexedGet + """let expando: *mut JSObject = GetExpandoObject(proxy);
 //if (!xpc::WrapperFactory::IsXrayWrapper(proxy) && (expando = GetExpandoObject(proxy))) {
 if expando.is_not_null() {
-  let flags = if set != 0 { JSRESOLVE_ASSIGNING } else { 0 } | JSRESOLVE_QUALIFIED;
+  let flags = if set { JSRESOLVE_ASSIGNING } else { 0 } | JSRESOLVE_QUALIFIED;
   if JS_GetPropertyDescriptorById(cx, expando, id, flags, desc) == 0 {
-    return 0;
+    return false;
   }
   if (*desc).obj.is_not_null() {
     // Pretend the property lives on the wrapper.
     (*desc).obj = proxy;
-    return 1;
+    return true;
   }
 }
 """ + namedGet + """
 (*desc).obj = ptr::mut_null();
-return 1;"""
+return true;"""
 
     def definition_body(self):
         return CGGeneric(self.getBody())
@@ -3646,7 +3646,7 @@ class CGDOMJSProxyHandler_defineProperty(CGAbstractExternMethod):
         args = [Argument('*mut JSContext', 'cx'), Argument('*mut JSObject', 'proxy'),
                 Argument('jsid', 'id'),
                 Argument('*const JSPropertyDescriptor', 'desc')]
-        CGAbstractExternMethod.__init__(self, descriptor, "defineProperty", "JSBool", args)
+        CGAbstractExternMethod.__init__(self, descriptor, "defineProperty", "bool", args)
         self.descriptor = descriptor
     def getBody(self):
         set = ""
@@ -3662,11 +3662,11 @@ class CGDOMJSProxyHandler_defineProperty(CGAbstractExternMethod):
                     "  let this = JS::from_raw(this);\n" +
                     "  let this = this.root();\n" +
                     CGIndenter(CGProxyIndexedSetter(self.descriptor)).define() +
-                    "  return 1;\n" +
+                    "  return true;\n" +
                     "}\n")
         elif self.descriptor.operations['IndexedGetter']:
             set += ("if GetArrayIndexFromId(cx, id).is_some() {\n" +
-                    "  return 0;\n" +
+                    "  return false;\n" +
                     "  //return ThrowErrorMessage(cx, MSG_NO_PROPERTY_SETTER, \"%s\");\n" +
                     "}\n") % self.descriptor.name
 
@@ -3689,10 +3689,10 @@ class CGDOMJSProxyHandler_defineProperty(CGAbstractExternMethod):
                     "  let this = this.root();\n" +
                     CGIndenter(CGProxyNamedGetter(self.descriptor)).define() +
                     "  if (found) {\n"
-                    "    return 0;\n" +
+                    "    return false;\n" +
                     "    //return ThrowErrorMessage(cx, MSG_NO_PROPERTY_SETTER, \"%s\");\n" +
                     "  }\n" +
-                    "  return 1;\n"
+                    "  return true;\n"
                     "}\n") % (self.descriptor.name)
         return set + """return proxyhandler::defineProperty_(%s);""" % ", ".join(a.name for a in self.args)
 
@@ -3702,8 +3702,8 @@ class CGDOMJSProxyHandler_defineProperty(CGAbstractExternMethod):
 class CGDOMJSProxyHandler_hasOwn(CGAbstractExternMethod):
     def __init__(self, descriptor):
         args = [Argument('*mut JSContext', 'cx'), Argument('*mut JSObject', 'proxy'),
-                Argument('jsid', 'id'), Argument('*mut JSBool', 'bp')]
-        CGAbstractExternMethod.__init__(self, descriptor, "hasOwn", "JSBool", args)
+                Argument('jsid', 'id'), Argument('*mut bool', 'bp')]
+        CGAbstractExternMethod.__init__(self, descriptor, "hasOwn", "bool", args)
         self.descriptor = descriptor
     def getBody(self):
         indexedGetter = self.descriptor.operations['IndexedGetter']
@@ -3715,8 +3715,8 @@ class CGDOMJSProxyHandler_hasOwn(CGAbstractExternMethod):
                        "  let this = JS::from_raw(this);\n" +
                        "  let this = this.root();\n" +
                        CGIndenter(CGProxyIndexedGetter(self.descriptor)).define() + "\n" +
-                       "  *bp = found as JSBool;\n" +
-                       "  return 1;\n" +
+                       "  *bp = found;\n" +
+                       "  return true;\n" +
                        "}\n\n")
         else:
             indexed = ""
@@ -3729,8 +3729,8 @@ class CGDOMJSProxyHandler_hasOwn(CGAbstractExternMethod):
                      "  let this = JS::from_raw(this);\n" +
                      "  let this = this.root();\n" +
                      CGIndenter(CGProxyNamedGetter(self.descriptor)).define() + "\n" +
-                     "  *bp = found as JSBool;\n"
-                     "  return 1;\n"
+                     "  *bp = found;\n"
+                     "  return true;\n"
                      "}\n" +
                      "\n")
         else:
@@ -3739,15 +3739,15 @@ class CGDOMJSProxyHandler_hasOwn(CGAbstractExternMethod):
         return indexed + """let expando: *mut JSObject = GetExpandoObject(proxy);
 if expando.is_not_null() {
   let mut b: JSBool = 1;
-  let ok: JSBool = JS_HasPropertyById(cx, expando, id, &mut b);
-  *bp = !!b;
-  if ok == 0 || *bp != 0 {
+  let ok = JS_HasPropertyById(cx, expando, id, &mut b) != 0;
+  *bp = b != 0;
+  if !ok || *bp {
     return ok;
   }
 }
 
-""" + named + """*bp = 0;
-return 1;"""
+""" + named + """*bp = false;
+return true;"""
 
     def definition_body(self):
         return CGGeneric(self.getBody())
@@ -3757,22 +3757,25 @@ class CGDOMJSProxyHandler_get(CGAbstractExternMethod):
         args = [Argument('*mut JSContext', 'cx'), Argument('*mut JSObject', 'proxy'),
                 Argument('*mut JSObject', 'receiver'), Argument('jsid', 'id'),
                 Argument('*mut JSVal', 'vp')]
-        CGAbstractExternMethod.__init__(self, descriptor, "get", "JSBool", args)
+        CGAbstractExternMethod.__init__(self, descriptor, "get", "bool", args)
         self.descriptor = descriptor
     def getBody(self):
         getFromExpando = """let expando = GetExpandoObject(proxy);
 if expando.is_not_null() {
   let mut hasProp = 0;
   if JS_HasPropertyById(cx, expando, id, &mut hasProp) == 0 {
-    return 0;
+    return false;
   }
 
   if hasProp != 0 {
-    return JS_GetPropertyById(cx, expando, id, vp);
+    return JS_GetPropertyById(cx, expando, id, vp) != 0;
   }
 }"""
 
-        templateValues = {'jsvalRef': '*vp'}
+        templateValues = {
+            'jsvalRef': '*vp',
+            'successCode': 'return true;',
+        }
 
         indexedGetter = self.descriptor.operations['IndexedGetter']
         if indexedGetter:
@@ -3811,15 +3814,15 @@ if expando.is_not_null() {
 %s
 let mut found = false;
 if !GetPropertyOnPrototype(cx, proxy, id, &mut found, vp) {
-  return 0;
+  return false;
 }
 
 if found {
-  return 1;
+  return true;
 }
 %s
 *vp = UndefinedValue();
-return 1;""" % (getIndexedOrExpando, getNamed)
+return true;""" % (getIndexedOrExpando, getNamed)
 
     def definition_body(self):
         return CGGeneric(self.getBody())
diff --git a/servo/src/components/script/dom/bindings/proxyhandler.rs b/servo/src/components/script/dom/bindings/proxyhandler.rs
index 97fa373b24f4..a3b61aa4be54 100644
--- a/servo/src/components/script/dom/bindings/proxyhandler.rs
+++ b/servo/src/components/script/dom/bindings/proxyhandler.rs
@@ -7,7 +7,7 @@
 use dom::bindings::utils::is_dom_proxy;
 use js::jsapi::{JSContext, jsid, JSPropertyDescriptor, JSObject, JSString, jschar};
 use js::jsapi::{JS_GetPropertyDescriptorById, JS_NewUCString, JS_malloc, JS_free};
-use js::jsapi::{JSBool, JS_DefinePropertyById, JS_NewObjectWithGivenProto};
+use js::jsapi::{JS_DefinePropertyById, JS_NewObjectWithGivenProto};
 use js::jsapi::{JS_ReportErrorFlagsAndNumber, JS_StrictPropertyStub};
 use js::jsapi::{JSREPORT_WARNING, JSREPORT_STRICT, JSREPORT_STRICT_MODE_ERROR};
 use js::jsapi::JS_DeletePropertyById2;
@@ -26,30 +26,32 @@ use std::mem::size_of;
 
 static JSPROXYSLOT_EXPANDO: u32 = 0;
 
-pub extern fn getPropertyDescriptor(cx: *mut JSContext, proxy: *mut JSObject, id: jsid,
-                                set: libc::c_int, desc: *mut JSPropertyDescriptor) -> libc::c_int {
+pub extern fn getPropertyDescriptor(cx: *mut JSContext, proxy: *mut JSObject,
+                                    id: jsid, set: bool,
+                                    desc: *mut JSPropertyDescriptor)
+                                    -> bool {
   unsafe {
     let handler = GetProxyHandler(proxy);
-    if InvokeGetOwnPropertyDescriptor(handler, cx, proxy, id, set, desc) == 0 {
-        return 0;
+    if !InvokeGetOwnPropertyDescriptor(handler, cx, proxy, id, set, desc) {
+        return false;
     }
     if (*desc).obj.is_not_null() {
-        return 1;
+        return true;
     }
 
     //let proto = JS_GetPrototype(proxy);
     let proto = GetObjectProto(proxy);
     if proto.is_null() {
         (*desc).obj = ptr::mut_null();
-        return 1;
+        return true;
     }
 
-    JS_GetPropertyDescriptorById(cx, proto, id, JSRESOLVE_QUALIFIED, mem::transmute(desc))
+    JS_GetPropertyDescriptorById(cx, proto, id, JSRESOLVE_QUALIFIED, desc) != 0
   }
 }
 
 pub fn defineProperty_(cx: *mut JSContext, proxy: *mut JSObject, id: jsid,
-                       desc: *mut JSPropertyDescriptor) -> JSBool {
+                       desc: *mut JSPropertyDescriptor) -> bool {
     static JSMSG_GETTER_ONLY: libc::c_uint = 160;
 
     unsafe {
@@ -61,39 +63,39 @@ pub fn defineProperty_(cx: *mut JSContext, proxy: *mut JSObject, id: jsid,
                                                 JSREPORT_WARNING | JSREPORT_STRICT |
                                                 JSREPORT_STRICT_MODE_ERROR,
                                                 Some(RUST_js_GetErrorMessage), ptr::mut_null(),
-                                                JSMSG_GETTER_ONLY);
+                                                JSMSG_GETTER_ONLY) != 0;
         }
 
         let expando = EnsureExpandoObject(cx, proxy);
         if expando.is_null() {
-            return 0;
+            return false;
         }
 
         return JS_DefinePropertyById(cx, expando, id, (*desc).value, (*desc).getter,
-                                     (*desc).setter, (*desc).attrs);
+                                     (*desc).setter, (*desc).attrs) != 0;
     }
 }
 
 pub extern fn defineProperty(cx: *mut JSContext, proxy: *mut JSObject, id: jsid,
-                             desc: *mut JSPropertyDescriptor) -> JSBool {
+                             desc: *mut JSPropertyDescriptor) -> bool {
     defineProperty_(cx, proxy, id, desc)
 }
 
 pub extern fn delete_(cx: *mut JSContext, proxy: *mut JSObject, id: jsid,
-                      bp: *mut bool) -> JSBool {
+                      bp: *mut bool) -> bool {
     unsafe {
         let expando = EnsureExpandoObject(cx, proxy);
         if expando.is_null() {
-            return 0;
+            return false;
         }
 
         let mut value = UndefinedValue();
         if JS_DeletePropertyById2(cx, expando, id, &mut value) == 0 {
-            return 0;
+            return false;
         }
 
         *bp = value.to_boolean();
-        return 1;
+        return true;
     }
 }