1 files changed, 1 insertions, 0 deletions
diff --git a/lib/arel/crud.rb b/lib/arel/crud.rb
index 6b3a776c6f..ef14439a1f 100644
--- a/lib/arel/crud.rb
+++ b/lib/arel/crud.rb
@@ -10,6 +10,7 @@ module Arel
       else
         relation = values.first.first.relation
       end
+      um.key= relation.primary_key
       um.table relation
       um.set values
       um.take @ast.limit.expr if @ast.limit