diff --git a/Lib/json/decoder.py b/Lib/json/decoder.py
index ff4bfcdcc407b9..62b4e07f1423ba 100644
--- a/Lib/json/decoder.py
+++ b/Lib/json/decoder.py
@@ -43,19 +43,19 @@ def __reduce__(self):
         return self.__class__, (self.msg, self.doc, self.pos)
 
 
-_CONSTANTS = {
+_CONSTANTS = frozendict({
     '-Infinity': NegInf,
     'Infinity': PosInf,
     'NaN': NaN,
-}
+})
 
 
 HEXDIGITS = re.compile(r'[0-9A-Fa-f]{4}', FLAGS)
 STRINGCHUNK = re.compile(r'(.*?)(["\\\x00-\x1f])', FLAGS)
-BACKSLASH = {
+BACKSLASH = frozendict({
     '"': '"', '\\': '\\', '/': '/',
     'b': '\b', 'f': '\f', 'n': '\n', 'r': '\r', 't': '\t',
-}
+})
 
 def _decode_uXXXX(s, pos, _m=HEXDIGITS.match):
     esc = _m(s, pos + 1)
diff --git a/Lib/json/tool.py b/Lib/json/tool.py
index 050c2fe2161e3e..14a5c9ecb74d13 100644
--- a/Lib/json/tool.py
+++ b/Lib/json/tool.py
@@ -22,13 +22,7 @@
     (?P<null>null)
 ''', re.VERBOSE)
 
-_group_to_theme_color = {
-    "key": "definition",
-    "string": "string",
-    "number": "number",
-    "boolean": "keyword",
-    "null": "keyword",
-}
+_group_to_theme_color = frozendict(key="definition",string="string",number="number",boolean="keyword",null="keyword")
 
 
 def _colorize_json(json_str, theme):