diff --git a/js/src/js.msg b/js/src/js.msg
index 4385d0223805..a0543737b18d 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -86,7 +86,8 @@ MSG_DEF(JSMSG_MISSING_FUN_ARG,         2, JSEXN_TYPEERR, "missing argument {0} w
 MSG_DEF(JSMSG_NOT_NONNULL_OBJECT,      1, JSEXN_TYPEERR, "{0} is not a non-null object")
 MSG_DEF(JSMSG_SET_NON_OBJECT_RECEIVER, 1, JSEXN_TYPEERR, "can't assign to properties of {0}: not an object")
 MSG_DEF(JSMSG_INVALID_DESCRIPTOR,      0, JSEXN_TYPEERR, "property descriptors must not specify a value or be writable when a getter or setter has been specified")
-MSG_DEF(JSMSG_OBJECT_NOT_EXTENSIBLE,   1, JSEXN_TYPEERR, "{0} is not extensible")
+MSG_DEF(JSMSG_OBJECT_NOT_EXTENSIBLE,   1, JSEXN_TYPEERR, "{0}: Object is not extensible")
+MSG_DEF(JSMSG_CANT_DEFINE_PROP_OBJECT_NOT_EXTENSIBLE, 2, JSEXN_TYPEERR, "can't define property {1}: {0} is not extensible")
 MSG_DEF(JSMSG_CANT_REDEFINE_PROP,      1, JSEXN_TYPEERR, "can't redefine non-configurable property {0}")
 MSG_DEF(JSMSG_CANT_APPEND_TO_ARRAY,    0, JSEXN_TYPEERR, "can't add elements past the end of an array if its length property is unwritable")
 MSG_DEF(JSMSG_CANT_REDEFINE_ARRAY_LENGTH, 0, JSEXN_TYPEERR, "can't redefine array length")
diff --git a/js/src/vm/NativeObject.cpp b/js/src/vm/NativeObject.cpp
index afc8ceff5bdb..1ae67548bf2d 100644
--- a/js/src/vm/NativeObject.cpp
+++ b/js/src/vm/NativeObject.cpp
@@ -1360,7 +1360,7 @@ js::NativeDefineProperty(ExclusiveContext* cx, HandleNativeObject obj, HandleId
     // Step 2.
     if (!shape) {
         if (!obj->nonProxyIsExtensible())
-            return result.fail(JSMSG_OBJECT_NOT_EXTENSIBLE);
+            return result.fail(JSMSG_CANT_DEFINE_PROP_OBJECT_NOT_EXTENSIBLE);
 
         // Fill in missing desc fields with defaults.
         CompletePropertyDescriptor(&desc);
diff --git a/js/src/vm/Xdr.h b/js/src/vm/Xdr.h
index 2502bd36e2cb..39aad3900193 100644
--- a/js/src/vm/Xdr.h
+++ b/js/src/vm/Xdr.h
@@ -29,11 +29,11 @@ namespace js {
  *
  *  https://developer.mozilla.org/en-US/docs/SpiderMonkey/Internals/Bytecode
  */
-static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 323;
+static const uint32_t XDR_BYTECODE_VERSION_SUBTRAHEND = 324;
 static const uint32_t XDR_BYTECODE_VERSION =
     uint32_t(0xb973c0de - XDR_BYTECODE_VERSION_SUBTRAHEND);
 
-static_assert(JSErr_Limit == 421,
+static_assert(JSErr_Limit == 422,
               "GREETINGS, POTENTIAL SUBTRAHEND INCREMENTER! If you added or "
               "removed MSG_DEFs from js.msg, you should increment "
               "XDR_BYTECODE_VERSION_SUBTRAHEND and update this assertion's "