diff --git a/xpcom/base/ErrorList.py b/xpcom/base/ErrorList.py
index fe461443585a..c72fc6f8ccdb 100755
--- a/xpcom/base/ErrorList.py
+++ b/xpcom/base/ErrorList.py
@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 import json
-from collections import OrderedDict
 
 
 class Mod:
@@ -21,7 +20,7 @@ class Mod:
         Mod.active = None
 
 
-modules = OrderedDict()
+modules = {}
 
 # To add error code to your module, you need to do the following:
 #
@@ -123,7 +122,7 @@ def SUCCESS(code):
 # Errors is an ordered dictionary, so that we can recover the order in which
 # they were defined. This is important for determining which name is the
 # canonical name for an error code.
-errors = OrderedDict()
+errors = {}
 
 # Standard "it worked" return value
 errors["NS_OK"] = 0
diff --git a/xpcom/reflect/xptinfo/xptcodegen.py b/xpcom/reflect/xptinfo/xptcodegen.py
index d089e8480790..f3ae66c96bfc 100644
--- a/xpcom/reflect/xptinfo/xptcodegen.py
+++ b/xpcom/reflect/xptinfo/xptcodegen.py
@@ -7,7 +7,6 @@
 
 import functools
 import json
-from collections import OrderedDict
 
 import buildconfig
 from perfecthash import PerfectHash
@@ -208,7 +207,7 @@ def link_to_cpp(interfaces, fd, header_fd):
     consts = []
     domobjects = []
     domobject_cache = {}
-    strings = OrderedDict()
+    strings = {}
 
     def lower_uuid(uuid):
         return (
@@ -242,7 +241,7 @@ def link_to_cpp(interfaces, fd, header_fd):
             # We've already seen this string.
             return strings[s]
         elif len(strings):
-            # Get the last string we inserted (should be O(1) on OrderedDict).
+            # Get the last string we inserted (should be O(1) on dict).
             last_s = next(reversed(strings))
             strings[s] = strings[last_s] + len(last_s) + 1
         else: