diff --git a/lib/mutations/command.rb b/lib/mutations/command.rb
index <HASH>..<HASH> 100644
--- a/lib/mutations/command.rb
+++ b/lib/mutations/command.rb
@@ -124,8 +124,10 @@ module Mutations
     end
 
     def merge_errors(hash)
-      @errors ||= ErrorHash.new
-      @errors.merge!(hash)
+      if hash.any?
+        @errors ||= ErrorHash.new
+        @errors.merge!(hash)
+      end
     end
 
   end
Bug fix: merging empty errors shouldn't make the command invalid