diff --git a/Lib/json/encoder.py b/Lib/json/encoder.py
--- a/Lib/json/encoder.py
+++ b/Lib/json/encoder.py
@@ -298,7 +298,7 @@
             elif value is False:
                 yield buf + 'false'
             elif isinstance(value, int):
-                yield buf + str(value)
+                yield buf + str(int(value))
             elif isinstance(value, float):
                 yield buf + _floatstr(value)
             else:
@@ -354,7 +354,7 @@
             elif key is None:
                 key = 'null'
             elif isinstance(key, int):
-                key = str(key)
+                key = str(int(key))
             elif _skipkeys:
                 continue
             else:
diff --git a/Modules/_json.c b/Modules/_json.c
--- a/Modules/_json.c
+++ b/Modules/_json.c
@@ -1366,9 +1366,15 @@
         return _steal_accumulate(acc, encoded);
     }
     else if (PyLong_Check(obj)) {
-        PyObject *encoded = PyObject_Str(obj);
-        if (encoded == NULL)
+        PyObject *encoded;
+        PyObject *longobj = PyNumber_Long(obj);
+        if (longobj == NULL)
+          return -1;
+        encoded = PyObject_Str(longobj);
+        if (encoded == NULL) {
+            Py_DECREF(longobj);
             return -1;
+        }
         return _steal_accumulate(acc, encoded);
     }
     else if (PyFloat_Check(obj)) {
@@ -1551,9 +1557,14 @@
                 goto bail;
         }
         else if (PyLong_Check(key)) {
-            kstr = PyObject_Str(key);
-            if (kstr == NULL)
+            PyObject *longobj = PyNumber_Long(key);
+            if (longobj == NULL)
+              goto bail;
+            kstr = PyObject_Str(longobj);
+            if (kstr == NULL) {
+                Py_DECREF(longobj);
                 goto bail;
+            }
         }
         else if (skipkeys) {
             Py_DECREF(item);