diff --git a/rest_framework/utils/encoders.py b/rest_framework/utils/encoders.py
index aa4542286..07508fb69 100644
--- a/rest_framework/utils/encoders.py
+++ b/rest_framework/utils/encoders.py
@@ -41,8 +41,7 @@ class JSONEncoder(json.JSONEncoder):
         elif isinstance(obj, datetime.timedelta):
             return str(obj.total_seconds())
         elif isinstance(obj, decimal.Decimal):
-            # Serializers will coerce decimals to strings by default.
-            return float(obj)
+            return str(obj)
         elif isinstance(obj, uuid.UUID):
             return str(obj)
         elif isinstance(obj, QuerySet):