diff --git a/js/libtextsecure.js b/js/libtextsecure.js
index 5c175c4f0..8609f6832 100644
--- a/js/libtextsecure.js
+++ b/js/libtextsecure.js
@@ -38308,6 +38308,30 @@ axolotlInternal.RecipientRecord = function() {
             });
         },
 
+        updateNumbers: function(groupId, numbers) {
+            return textsecure.storage.axolotl.getGroup(groupId).then(function(group) {
+                if (group === undefined)
+                    throw new Error("Tried to update numbers for unknown group");
+
+                if (numbers.filter(function(number) { return !textsecure.utils.isNumberSane(number); }).length > 0)
+                    throw new Error("Invalid number in new group members");
+
+                if (group.numbers.filter(function(number) { return numbers.indexOf(number) < 0 }).length > 0)
+                    throw new Error("Attempted to remove numbers from group with an UPDATE");
+
+                var added = numbers.filter(function(number) { return group.numbers.indexOf(number) < 0; });
+
+                return textsecure.storage.groups.addNumbers(groupId, added).then(function(newGroup) {
+                    if (newGroup.length != numbers.length ||
+                        newGroup.filter(function(number) { return numbers.indexOf(number) < 0; }).length != 0) {
+                        throw new Error("Error calculating group member difference");
+                    }
+
+                    return added;
+                });
+            });
+        },
+
         needUpdateByDeviceRegistrationId: function(groupId, number, encodedNumber, registrationId) {
             return textsecure.storage.axolotl.getGroup(groupId).then(function(group) {
                 if (group === undefined)
@@ -38779,21 +38803,14 @@ function processDecrypted(decrypted, source) {
                     if (decrypted.group.avatar !== null)
                         promises.push(handleAttachment(decrypted.group.avatar));
 
-                    if (decrypted.group.members.filter(function(number) { return !textsecure.utils.isNumberSane(number); }).length != 0)
-                        throw new Error("Invalid number in new group members");
+                    return textsecure.storage.groups.updateNumbers(
+                        decrypted.group.id, decrypted.group.members
+                    ).then(function(added) {
+                        decrypted.group.added = added;
 
-                    if (existingGroup.filter(function(number) { decrypted.group.members.indexOf(number) < 0 }).length != 0)
-                        throw new Error("Attempted to remove numbers from group with an UPDATE");
-                    decrypted.group.added = decrypted.group.members.filter(function(number) { return existingGroup.indexOf(number) < 0; });
-
-                    return textsecure.storage.groups.addNumbers(decrypted.group.id, decrypted.group.added).then(function(newGroup) {
-                        if (newGroup.length != decrypted.group.members.length ||
-                            newGroup.filter(function(number) { return decrypted.group.members.indexOf(number) < 0; }).length != 0) {
-                            throw new Error("Error calculating group member difference");
-                        }
-
-                        //TODO: Also follow this path if avatar + name haven't changed (ie we should start storing those)
-                        if (decrypted.group.avatar === null && decrypted.group.added.length == 0 && decrypted.group.name === null) {
+                        if (decrypted.group.avatar === null &&
+                            decrypted.group.added.length == 0 &&
+                            decrypted.group.name === null) {
                             return;
                         }
 
@@ -39675,6 +39692,9 @@ function generateKeys(count, progressCallback) {
                                     groupDetails.members, groupDetails.id
                                 );
                             } else {
+                                return textsecure.storage.groups.updateNumbers(
+                                    groupDetails.id, groupDetails.members
+                                );
                             }
                         }).then(function() {
                             var ev = new Event('group');
diff --git a/libtextsecure/helpers.js b/libtextsecure/helpers.js
index 49431f34a..90e50fdca 100644
--- a/libtextsecure/helpers.js
+++ b/libtextsecure/helpers.js
@@ -192,21 +192,14 @@ function processDecrypted(decrypted, source) {
                     if (decrypted.group.avatar !== null)
                         promises.push(handleAttachment(decrypted.group.avatar));
 
-                    if (decrypted.group.members.filter(function(number) { return !textsecure.utils.isNumberSane(number); }).length != 0)
-                        throw new Error("Invalid number in new group members");
-
-                    if (existingGroup.filter(function(number) { decrypted.group.members.indexOf(number) < 0 }).length != 0)
-                        throw new Error("Attempted to remove numbers from group with an UPDATE");
-                    decrypted.group.added = decrypted.group.members.filter(function(number) { return existingGroup.indexOf(number) < 0; });
-
-                    return textsecure.storage.groups.addNumbers(decrypted.group.id, decrypted.group.added).then(function(newGroup) {
-                        if (newGroup.length != decrypted.group.members.length ||
-                            newGroup.filter(function(number) { return decrypted.group.members.indexOf(number) < 0; }).length != 0) {
-                            throw new Error("Error calculating group member difference");
-                        }
-
-                        //TODO: Also follow this path if avatar + name haven't changed (ie we should start storing those)
-                        if (decrypted.group.avatar === null && decrypted.group.added.length == 0 && decrypted.group.name === null) {
+                    return textsecure.storage.groups.updateNumbers(
+                        decrypted.group.id, decrypted.group.members
+                    ).then(function(added) {
+                        decrypted.group.added = added;
+
+                        if (decrypted.group.avatar === null &&
+                            decrypted.group.added.length == 0 &&
+                            decrypted.group.name === null) {
                             return;
                         }
 
diff --git a/libtextsecure/message_receiver.js b/libtextsecure/message_receiver.js
index 2b3c91445..6e29ea536 100644
--- a/libtextsecure/message_receiver.js
+++ b/libtextsecure/message_receiver.js
@@ -202,6 +202,9 @@
                                     groupDetails.members, groupDetails.id
                                 );
                             } else {
+                                return textsecure.storage.groups.updateNumbers(
+                                    groupDetails.id, groupDetails.members
+                                );
                             }
                         }).then(function() {
                             var ev = new Event('group');
diff --git a/libtextsecure/storage/groups.js b/libtextsecure/storage/groups.js
index 5cde3f1da..b626c0bc7 100644
--- a/libtextsecure/storage/groups.js
+++ b/libtextsecure/storage/groups.js
@@ -143,6 +143,30 @@
             });
         },
 
+        updateNumbers: function(groupId, numbers) {
+            return textsecure.storage.axolotl.getGroup(groupId).then(function(group) {
+                if (group === undefined)
+                    throw new Error("Tried to update numbers for unknown group");
+
+                if (numbers.filter(function(number) { return !textsecure.utils.isNumberSane(number); }).length > 0)
+                    throw new Error("Invalid number in new group members");
+
+                if (group.numbers.filter(function(number) { return numbers.indexOf(number) < 0 }).length > 0)
+                    throw new Error("Attempted to remove numbers from group with an UPDATE");
+
+                var added = numbers.filter(function(number) { return group.numbers.indexOf(number) < 0; });
+
+                return textsecure.storage.groups.addNumbers(groupId, added).then(function(newGroup) {
+                    if (newGroup.length != numbers.length ||
+                        newGroup.filter(function(number) { return numbers.indexOf(number) < 0; }).length != 0) {
+                        throw new Error("Error calculating group member difference");
+                    }
+
+                    return added;
+                });
+            });
+        },
+
         needUpdateByDeviceRegistrationId: function(groupId, number, encodedNumber, registrationId) {
             return textsecure.storage.axolotl.getGroup(groupId).then(function(group) {
                 if (group === undefined)