diff --git a/rest_framework/utils/encoders.py b/rest_framework/utils/encoders.py
index 17cbd3cd5..b48b8ec0f 100644
--- a/rest_framework/utils/encoders.py
+++ b/rest_framework/utils/encoders.py
@@ -59,11 +59,11 @@ class JSONEncoder(json.JSONEncoder):
             # internals.
 
             if o != o:
-                text = 'null'
+                text = '"NaN"'
             elif o == _inf:
-                text = 'null'
+                text = '"Infinity"'
             elif o == _neginf:
-                text = 'null'
+                text = '"-Infinity"'
             else:
                 return _repr(o)