diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 41d6105ca..1d4f8be10 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -534,6 +534,9 @@ class Field(object):
         errors = []
         for validator in self.validators:
             if hasattr(validator, 'set_context'):
+                # Need to make a copy, because validator instances often
+                # are initialised globally
+                validator = copy.deepcopy(validator)
                 validator.set_context(self)
 
             try: