diff --git a/app/models/budget/ballot/line.rb b/app/models/budget/ballot/line.rb
index 8b0849a19..0268ecc74 100644
--- a/app/models/budget/ballot/line.rb
+++ b/app/models/budget/ballot/line.rb
@@ -18,10 +18,10 @@ class Budget
       before_validation :set_denormalized_ids
 
       def check_enough_resources
-        ballot.lock!
-
-        unless ballot.enough_resources?(investment)
-          errors.add(:resources, ballot.not_enough_resources_error)
+        ballot.with_lock do
+          unless ballot.enough_resources?(investment)
+            errors.add(:resources, ballot.not_enough_resources_error)
+          end
         end
       end
 
diff --git a/app/models/poll/answer.rb b/app/models/poll/answer.rb
index b99ffcef6..e3fbef6f7 100644
--- a/app/models/poll/answer.rb
+++ b/app/models/poll/answer.rb
@@ -38,10 +38,10 @@ class Poll::Answer < ApplicationRecord
     def max_votes
       return if !question || !author || persisted?
 
-      author.lock!
-
-      if question.answers.by_author(author).count >= question.max_votes
-        errors.add(:answer, "Maximum number of votes per user exceeded")
+      author.with_lock do
+        if question.answers.by_author(author).count >= question.max_votes
+          errors.add(:answer, "Maximum number of votes per user exceeded")
+        end
       end
     end
 end