diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 5730ca571..d2079d5d6 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -688,8 +688,22 @@ class NullBooleanField(Field):
         'invalid': _('"{input}" is not a valid boolean.')
     }
     initial = None
-    TRUE_VALUES = {'t', 'T', 'true', 'True', 'TRUE', '1', 1, True}
-    FALSE_VALUES = {'f', 'F', 'false', 'False', 'FALSE', '0', 0, 0.0, False}
+    TRUE_VALUES = {
+        't', 'T',
+        'y', 'Y', 'yes', 'YES',
+        'true', 'True', 'TRUE',
+        'on', 'On', 'ON',
+        '1', 1,
+        True
+    }
+    FALSE_VALUES = {
+        'f', 'F',
+        'n', 'N', 'no', 'NO',
+        'false', 'False', 'FALSE',
+        'off', 'Off', 'OFF',
+        '0', 0, 0.0,
+        False
+    }
     NULL_VALUES = {'n', 'N', 'null', 'Null', 'NULL', '', None}
 
     def __init__(self, **kwargs):
@@ -698,12 +712,15 @@ class NullBooleanField(Field):
         super(NullBooleanField, self).__init__(**kwargs)
 
     def to_internal_value(self, data):
-        if data in self.TRUE_VALUES:
-            return True
-        elif data in self.FALSE_VALUES:
-            return False
-        elif data in self.NULL_VALUES:
-            return None
+        try:
+            if data in self.TRUE_VALUES:
+                return True
+            elif data in self.FALSE_VALUES:
+                return False
+            elif data in self.NULL_VALUES:
+                return None
+        except TypeError:  # Input is an unhashable type
+            pass
         self.fail('invalid', input=data)
 
     def to_representation(self, value):
diff --git a/tests/test_fields.py b/tests/test_fields.py
index d6b233227..c3d2bf57d 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -587,7 +587,7 @@ class TestBooleanField(FieldValues):
             [],
             {},
         )
-        field = serializers.BooleanField()
+        field = self.field
         for input_value in inputs:
             with pytest.raises(serializers.ValidationError) as exc_info:
                 field.run_validation(input_value)
@@ -595,7 +595,7 @@ class TestBooleanField(FieldValues):
             assert exc_info.value.detail == expected
 
 
-class TestNullBooleanField(FieldValues):
+class TestNullBooleanField(TestBooleanField):
     """
     Valid and invalid values for `BooleanField`.
     """