diff -r 94710cbcac47 Lib/json/encoder.py
--- a/Lib/json/encoder.py	Thu Sep 01 13:55:33 2016 -0400
+++ b/Lib/json/encoder.py	Thu Sep 01 14:46:57 2016 -0500
@@ -221,7 +221,7 @@
             _encoder = encode_basestring
 
         def floatstr(o, allow_nan=self.allow_nan,
-                _repr=float.__repr__, _inf=INFINITY, _neginf=-INFINITY):
+                _repr=float.__str__, _inf=INFINITY, _neginf=-INFINITY):
             # Check for specials.  Note that this type of test is processor
             # and/or platform-specific, so do tests which don't depend on the
             # internals.
@@ -238,7 +238,7 @@
             if not allow_nan:
                 raise ValueError(
                     "Out of range float values are not JSON compliant: " +
-                    repr(o))
+                    str(o))
 
             return text
 
diff -r 94710cbcac47 Modules/_json.c
--- a/Modules/_json.c	Thu Sep 01 13:55:33 2016 -0400
+++ b/Modules/_json.c	Thu Sep 01 14:46:57 2016 -0500
@@ -1465,7 +1465,7 @@
             return PyUnicode_FromString("NaN");
         }
     }
-    return PyFloat_Type.tp_repr(obj);
+    return PyFloat_Type.tp_str(obj);
 }
 
 static PyObject *