diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index 85b65ecf1a..a150ba4acf 100644
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -40,6 +40,7 @@ module ActiveRecord
       full_messages = []
 
       each do |attribute, messages|
+        messages = Array.wrap(messages)
         next if messages.empty?
 
         if attribute == :base