diff --git a/gems/activerecord/6.0/activerecord.rbs b/gems/activerecord/6.0/activerecord.rbs
index 8ff5dc89..32d98175 100644
--- a/gems/activerecord/6.0/activerecord.rbs
+++ b/gems/activerecord/6.0/activerecord.rbs
@@ -353,6 +353,7 @@ interface _ActiveRecord_Relation[Model, PrimaryKey]
   def find_each: (?batch_size: Integer, ?start: Integer, ?finish: Integer, ?error_on_ignore: bool) { (Model) -> void } -> nil
   def find_in_batches: (?batch_size: Integer, ?start: Integer, ?finish: Integer, ?error_on_ignore: bool) { (Array[Model]) -> void } -> nil
   def in_batches: (?of: Integer, ?start: Integer, ?finish: Integer, ?load: bool, ?error_on_ignore: bool, ?order: untyped) { (self) -> void } -> nil
+  def sum: (?untyped? column_name) -> Integer
   def destroy_all: () -> untyped
   def delete_all: () -> untyped
   def update_all: (untyped) -> untyped
@@ -435,6 +436,7 @@ interface _ActiveRecord_Relation_ClassMethods[Model, Relation, PrimaryKey]
   def find_each: (?batch_size: Integer, ?start: Integer, ?finish: Integer, ?error_on_ignore: bool) { (Model) -> void } -> nil
   def find_in_batches: (?batch_size: Integer, ?start: Integer, ?finish: Integer, ?error_on_ignore: bool) { (Array[Model]) -> void } -> nil
   def in_batches: (?of: Integer, ?start: Integer, ?finish: Integer, ?load: bool, ?error_on_ignore: bool, ?order: untyped) { (Relation) -> void } -> nil
+  def sum: (?untyped? column_name) -> Integer
   def destroy_all: () -> untyped
   def delete_all: () -> untyped
   def update_all: (untyped) -> untyped