diff --git a/commentjson/commentjson.py b/commentjson/commentjson.py
index 63f1081..4073d91 100755
--- a/commentjson/commentjson.py
+++ b/commentjson/commentjson.py
@@ -36,7 +36,7 @@
     ?value: object
           | array
           | string
-          | SIGNED_NUMBER      -> number
+          | SIGNED_NUMBER_NAN  -> number
           | "true"             -> true
           | "false"            -> false
           | "null"             -> null
@@ -48,6 +48,8 @@
     COMMENT: /(#|\\/\\/)[^\\n]*/
     TRAILING_COMMA: ","
 
+    SIGNED_NUMBER_NAN: SIGNED_NUMBER | "NaN"
+
     %import common.ESCAPED_STRING
     %import common.SIGNED_NUMBER
     %import common.WS