--- a/toolkit/components/telemetry/docs/data/core-ping.rst
+++ b/toolkit/components/telemetry/docs/data/core-ping.rst
@@ -52,16 +52,18 @@ Structure:
       "durations": <integer>, // combined duration, in seconds, of all
                                     // sessions since last upload
       "searches": <object>, // Optional, object of search use counts in the
                             // format: { "engine.source": <pos integer> }
                             // e.g.: { "yahoo.suggestion": 3, "other.listitem": 1 }
       "experiments": [<string>, /* … */], // Optional, array of identifiers
                                     // for the active experiments
       "flashUsage": <integer>, // number of times flash plugin is played since last upload
+      "defaultBrowser": <boolean> // true if the user has set Firefox as default browser
+
     }
 
 Field details
 -------------
 
 device
 ~~~~~~
 The ``device`` field is filled in with information specified by the hardware
@@ -181,17 +183,17 @@ HTTP "Date" header
 This header is used to track the submission date of the core ping in the format
 specified by
 `rfc 2616 sec 14.18 <https://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.18>`_,
 et al (e.g. "Tue, 01 Feb 2011 14:00:00 GMT").
 
 
 Version history
 ---------------
-
+* v10: added ``defaultBrowser`` to know if the user has set Firefox as default browser
 * v9: changed ``arch`` to contain device arch rather than the one we built against
 * v8: added ``flashUsage``
 * v7: added ``sessionCount`` & ``sessionDuration``  & ``campaignId``
 * v6: added ``searches``
 * v5: added ``created`` & ``tz``
 * v4: ``profileDate`` will return package install time when times.json is not available
 * v3: added ``defaultSearch``
 * v2: added ``distributionId``