diff --git a/rest_framework/exceptions.py b/rest_framework/exceptions.py
index 12fd41931..d885ba643 100644
--- a/rest_framework/exceptions.py
+++ b/rest_framework/exceptions.py
@@ -92,7 +92,7 @@ class APIException(Exception):
         self.detail = _get_error_details(detail, code)
 
     def __str__(self):
-        return self.detail
+        return six.text_type(self.detail)
 
     def get_codes(self):
         """
@@ -136,9 +136,6 @@ class ValidationError(APIException):
 
         self.detail = _get_error_details(detail, code)
 
-    def __str__(self):
-        return six.text_type(self.detail)
-
 
 class ParseError(APIException):
     status_code = status.HTTP_400_BAD_REQUEST