--- a/mobile/android/base/java/org/mozilla/gecko/telemetry/pingbuilders/TelemetryCorePingBuilder.java
+++ b/mobile/android/base/java/org/mozilla/gecko/telemetry/pingbuilders/TelemetryCorePingBuilder.java
@@ -41,17 +41,17 @@ import java.util.concurrent.TimeUnit;
  */
 public class TelemetryCorePingBuilder extends TelemetryPingBuilder {
     private static final String LOGTAG = StringUtils.safeSubstring(TelemetryCorePingBuilder.class.getSimpleName(), 0, 23);
 
     // For legacy reasons, this preference key is not namespaced with "core".
     private static final String PREF_SEQ_COUNT = "telemetry-seqCount";
 
     private static final String NAME = "core";
-    private static final int VERSION_VALUE = 8; // For version history, see toolkit/components/telemetry/docs/core-ping.rst
+    private static final int VERSION_VALUE = 9; // For version history, see toolkit/components/telemetry/docs/core-ping.rst
     private static final String OS_VALUE = "Android";
 
     private static final String ARCHITECTURE = "arch";
     private static final String CAMPAIGN_ID = "campaignId";
     private static final String CLIENT_ID = "clientId";
     private static final String DEFAULT_SEARCH_ENGINE = "defaultSearch";
     private static final String DEVICE = "device";
     private static final String DISTRIBUTION_ID = "distributionId";

--- a/toolkit/components/telemetry/docs/data/core-ping.rst
+++ b/toolkit/components/telemetry/docs/data/core-ping.rst
@@ -22,17 +22,17 @@ Submission will be per the Edge server s
 Note: Counts below (e.g. search & usage times) are “since the last
 ping”, not total for the whole application lifetime.
 
 Structure:
 
 .. code-block:: js
 
     {
-      "v": 7, // ping format version
+      "v": 9, // ping format version
       "clientId": <string>, // client id, e.g.
                             // "c641eacf-c30c-4171-b403-f077724e848a"
       "seq": <positive integer>, // running ping counter, e.g. 3
       "locale": <string>, // application locale, e.g. "en-US"
       "os": <string>, // OS name.
       "osversion": <string>, // OS version.
       "device": <string>, // Build.MANUFACTURER + " - " + Build.MODEL
                           // where manufacturer is truncated to 12 characters
@@ -153,16 +153,17 @@ 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
 ---------------
+* v9: changed ``arch`` to contain device arch rather than the one we built against
 * v8: added ``flashUsage``
 * v7: added ``sessionCount`` & ``sessionDuration``
 * 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``
 * v1: initial version - shipped in `Fennec 45 <https://bugzilla.mozilla.org/show_bug.cgi?id=1205835>`_.