diff --git a/docs/release-notes.md b/docs/release-notes.md
index 6ba5c39..c6775f6 100644
--- a/docs/release-notes.md
+++ b/docs/release-notes.md
@@ -9,6 +9,16 @@ Medium version numbers (0.x.0) may include API changes, in line with the [deprec
 Major version numbers (x.0.0) are reserved for substantial project milestones.
 
 
+### 0.3.13
+
+**Date:** [2nd April 2020]
+
+* Added check on `None` in `to_representation` methods in:
+    * ['CharField'][CharField]
+    * ['IntegerField'][IntegerField]
+    * ['FloatField'][FloatField]
+    * ['DictField'][DictField]
+
 ### 0.3.12
 
 **Date:** [21th January 2020]
@@ -201,6 +211,9 @@ class TwoSer(Ser):
 [ListField]: api-guid/fields.md#-listfield
 [JsonField]: api-guid/fields.md#-jsonfield
 [DictField]: api-guid/fields.md#-dictfield
+[IntegerField]: api-guid/fields.md#-integerfield
+[FloatField]: api-guid/fields.md#-floatfield
+[CharField]: api-guid/fields.md#-charfield
 [SerializerMethodField]: api-guid/fields.md#-serializermethodfield
 [InheritSerializers]: api-guid/serializers.md#serializer-inheritance
 [RegexValidator]: api-guid/validators.md#regexvalidator
diff --git a/rest_framework/__init__.py b/rest_framework/__init__.py
index a5dfa68..21286a7 100644
--- a/rest_framework/__init__.py
+++ b/rest_framework/__init__.py
@@ -8,7 +8,7 @@
          __/ |
         |___/
 """
-VERSION = (0, 3, 12)
+VERSION = (0, 3, 13)
 
 __title__ = 'Python-Rest-Framework'
 __author__ = 'Deys Timofey'
diff --git a/rest_framework/serializers/fields.py b/rest_framework/serializers/fields.py
index 718c9c3..0fe3e9a 100644
--- a/rest_framework/serializers/fields.py
+++ b/rest_framework/serializers/fields.py
@@ -490,6 +490,8 @@ def to_representation(self, value):
         :rtype: str
 
         """
+        if value is None:
+            return None
         return six.text_type(value)
 
 
@@ -567,6 +569,8 @@ def to_representation(self, value):
         :rtype: int
 
         """
+        if value is None:
+            return value
         return int(value)
 
 
@@ -642,6 +646,8 @@ def to_representation(self, value):
         :rtype: float
 
         """
+        if value is None:
+            return value
         return float(value)
 
 
@@ -1305,6 +1311,8 @@ def to_representation(self, value):
         :rtype: str
 
         """
+        if value is None:
+            return value
         return {
             six.text_type(key): self.child._to_representation(val) if val is not None else None
             for key, val in six.iteritems(value)
diff --git a/tests/test_fields.py b/tests/test_fields.py
index 262f2ad..c014ea3 100644
--- a/tests/test_fields.py
+++ b/tests/test_fields.py
@@ -499,7 +499,8 @@ class CharFieldTest(BaseFieldTestCase):
     to_representation_cases = (
         {'data': {'value': '123'}, 'return': '123'},
         {'data': {'value': 123}, 'return': '123'},
-        {'data': {'value': 'qwe'}, 'return': 'qwe'}
+        {'data': {'value': 'qwe'}, 'return': 'qwe'},
+        {'data': {'value': None}, 'return': None},
     )  # Cases, to test the performance of `.to_representation()`.
     to_internal_value_cases = (
         {'data': {'data': '123'}, 'return': '123'},
@@ -560,6 +561,7 @@ class TestIntegerField(BaseFieldTestCase):
         {'data': {'value': 123}, 'return': 123},
         {'data': {'value': '123'}, 'return': 123},
         {'data': {'value': 'qwe'}, 'exceptions': (ValueError,)},
+        {'data': {'value': None}, 'return': None},
     )  # Cases, to test the performance of `.to_representation()`.
     to_internal_value_cases = (
         {'data': {'data': 123}, 'return': 123},
@@ -609,6 +611,7 @@ class TestFloatField(BaseFieldTestCase):
         {'data': {'value': 123}, 'return': 123.0},
         {'data': {'value': '123'}, 'return': 123.0},
         {'data': {'value': 'qwe'}, 'exceptions': (ValueError,)},
+        {'data': {'value': None}, 'return': None},
     )  # Cases, to test the performance of `.to_representation()`.
     to_internal_value_cases = (
         {'data': {'data': 123}, 'return': 123.0},
@@ -949,7 +952,8 @@ class TestJsonField(BaseFieldTestCase):
         {'data': {'value': {'123': 123}}, 'return': '{"123": 123}'},
         {'data': {'value': {'123': [123, '123']}}, 'return': '{"123": [123, "123"]}'},
         {'data': {'value': lambda: None}, 'exceptions': (ValidationError,)},
-        {'data': {'value': {123: 123}}, 'return': '{"123": 123}'}
+        {'data': {'value': {123: 123}}, 'return': '{"123": 123}'},
+        {'data': {'value': None}, 'return': 'null'},
     )  # Cases, to test the performance of `.to_representation()`.
     to_internal_value_cases = (
         {'data': {'data': {}}, 'return': {}},
@@ -998,6 +1002,7 @@ class TestDictField(BaseFieldTestCase):
         {'data': {'value': 123}, 'exceptions': (AttributeError,)},
         {'data': {'value': lambda: None}, 'exceptions': (AttributeError,)},
         {'data': {'value': {123: 123}}, 'return': {'123': 123}},
+        {'data': {'value': None}, 'return': None},
         {'data': {'value': {123: [123]}}, 'params': {'child': IntegerField()}, 'exceptions': (TypeError,)}
     )  # Cases, to test the performance of `.to_representation()`.
     to_internal_value_cases = (