diff --git a/jsonschema/_types.py b/jsonschema/_types.py
index a71a4e34b..dd5b784b9 100644
--- a/jsonschema/_types.py
+++ b/jsonschema/_types.py
@@ -1,6 +1,5 @@
 import numbers
 
-from pyrsistent import pmap
 import attr
 
 from jsonschema.compat import int_types, str_types
@@ -61,7 +60,7 @@ class TypeChecker(object):
 
             The initial mapping of types to their checking functions.
     """
-    _type_checkers = attr.ib(default=pmap(), converter=pmap)
+    _type_checkers = attr.ib(default=dict(), converter=dict)
 
     def is_type(self, instance, type):
         """
@@ -131,8 +130,10 @@ def redefine_many(self, definitions=()):
 
             A new `TypeChecker` instance.
         """
+        new_checkers = dict(self._type_checkers)
+        new_checkers.update(definitions)
         return attr.evolve(
-            self, type_checkers=self._type_checkers.update(definitions),
+            self, type_checkers=new_checkers,
         )
 
     def remove(self, *types):
@@ -159,7 +160,8 @@ def remove(self, *types):
         checkers = self._type_checkers
         for each in types:
             try:
-                checkers = checkers.remove(each)
+                checkers = dict(checkers)
+                checkers.pop(each)
             except KeyError:
                 raise UndefinedTypeCheck(each)
         return attr.evolve(self, type_checkers=checkers)
diff --git a/setup.cfg b/setup.cfg
index 2ae0461bb..9ac2aa56b 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -30,7 +30,6 @@ install_requires =
     attrs>=17.4.0
     functools32;python_version<'3'
     importlib_metadata;python_version<'3.8'
-    pyrsistent>=0.14.0
     six>=1.11.0
 
 [options.extras_require]