diff --git a/service/src/main/java/org/whispersystems/textsecuregcm/storage/Accounts.java b/service/src/main/java/org/whispersystems/textsecuregcm/storage/Accounts.java
index 2fbe8c46f..a26c43490 100644
--- a/service/src/main/java/org/whispersystems/textsecuregcm/storage/Accounts.java
+++ b/service/src/main/java/org/whispersystems/textsecuregcm/storage/Accounts.java
@@ -430,7 +430,7 @@ public class Accounts extends AbstractDynamoDbStore {
       } catch (final JsonProcessingException e) {
         throw new IllegalArgumentException(e);
       } catch (final TransactionCanceledException e) {
-        if (e.hasCancellationReasons() && e.cancellationReasons().size() == 6) {
+        if (e.hasCancellationReasons() && e.cancellationReasons().size() == 6 + additionalWriteItems.size()) {
           // the cancellation reasons map to the write items:
           // 0. phone number constraint delete - no conditions
           // 1. phone number constraint put - conditional on the key not existing (it is deleted by 0)
@@ -438,6 +438,8 @@ public class Accounts extends AbstractDynamoDbStore {
           // 3. pni constraint put - conditional on the key not existing (it is deleted by 2)
           // 4. deleted accounts delete - no conditions
           // 5. account update - conditional on #version = :version
+          // 6. additional write items…
+          // 7. additional write items…
           if (CONDITIONAL_CHECK_FAILED.equals(e.cancellationReasons().get(5).code())) {
             // the #version = :version condition failed, which indicates a concurrent update
             throw new ContestedOptimisticLockException();