diff --git a/tensorflow_serving/g3doc/api_rest.md b/tensorflow_serving/g3doc/api_rest.md
index 8edd1d3acbc..6818ab7051f 100644
--- a/tensorflow_serving/g3doc/api_rest.md
+++ b/tensorflow_serving/g3doc/api_rest.md
@@ -392,7 +392,7 @@ such values. This implies that requests like the following one are valid:
 {
   "example": [
     {
-      "sensor_readings": [ 1.0, -3.14, Nan, Infinity ]
+      "sensor_readings": [ 1.0, -3.14, NaN, Infinity ]
     }
   ]
 }